14 files changed, 133 insertions, 98 deletions

diff --git a/arch/alpha/include/asm/uaccess.h b/arch/alpha/include/asm/uaccess.h
index 466e42e96bfa..94f587535dee 100644
--- a/arch/alpha/include/asm/uaccess.h
+++ b/arch/alpha/include/asm/uaccess.h
@@ -396,11 +396,12 @@ copy_to_user(void __user *to, const void *from, long n)
 extern inline long
 copy_from_user(void *to, const void __user *from, long n)
 {
+        long res = n;
         if (likely(__access_ok((unsigned long)from, n, get_fs())))
-                n = __copy_tofrom_user_nocheck(to, (__force void *)from, n);
-        else
-                memset(to, 0, n);
-        return n;
+                res = __copy_from_user_inatomic(to, from, n);
+        if (unlikely(res))
+                memset(to + (n - res), 0, res);
+        return res;
 }
 
 extern void __do_clear_user(void);
diff --git a/arch/alpha/lib/copy_user.S b/arch/alpha/lib/copy_user.S
index 2238068b1b40..509f62b65311 100644
--- a/arch/alpha/lib/copy_user.S
+++ b/arch/alpha/lib/copy_user.S
@@ -126,22 +126,8 @@ $65:
         bis $31,$31,$0
 $41:
 $35:
-$exitout:
-        ret $31,($28),1
-
 $exitin:
-        /* A stupid byte-by-byte zeroing of the rest of the output
-           buffer.  This cures security holes by never leaving 
-           random kernel data around to be copied elsewhere.  */
-
-        mov $0,$1
-$101:
-        EXO ( ldq_u $2,0($6) )
-        subq $1,1,$1
-        mskbl $2,$6,$2
-        EXO ( stq_u $2,0($6) )
-        addq $6,1,$6
-        bgt $1,$101
+$exitout:
         ret $31,($28),1
 
         .end __copy_user
diff --git a/arch/alpha/lib/ev6-copy_user.S b/arch/alpha/lib/ev6-copy_user.S
index debcc3b6b704..be720b518af9 100644
--- a/arch/alpha/lib/ev6-copy_user.S
+++ b/arch/alpha/lib/ev6-copy_user.S
@@ -228,33 +228,12 @@ $dirtyentry:
         bgt $0,$onebyteloop     # U  .. .. ..   : U L U L
 
 $zerolength:
+$exitin:
 $exitout:                       # Destination for exception recovery(?)
         nop                     # .. .. .. E
         nop                     # .. .. E  ..
         nop                     # .. E  .. ..
         ret $31,($28),1         # L0 .. .. ..   : L U L U
 
-$exitin:
-
-        /* A stupid byte-by-byte zeroing of the rest of the output
-           buffer.  This cures security holes by never leaving 
-           random kernel data around to be copied elsewhere.  */
-
-        nop
-        nop
-        nop
-        mov     $0,$1
-
-$101:
-        EXO ( stb $31,0($6) )   # L
-        subq $1,1,$1            # E
-        addq $6,1,$6            # E
-        bgt $1,$101             # U
-
-        nop
-        nop
-        nop
-        ret $31,($28),1         # L0
-
         .end __copy_user
         EXPORT_SYMBOL(__copy_user)
diff --git a/arch/arc/kernel/signal.c b/arch/arc/kernel/signal.c
index 6cb3736b6b83..d347bbc086fe 100644
--- a/arch/arc/kernel/signal.c
+++ b/arch/arc/kernel/signal.c
@@ -107,13 +107,13 @@ static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
         struct user_regs_struct uregs;
 
         err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
-        if (!err)
-                set_current_blocked(&set);
-
         err |= __copy_from_user(&uregs.scratch,
                                 &(sf->uc.uc_mcontext.regs.scratch),
                                 sizeof(sf->uc.uc_mcontext.regs.scratch));
+        if (err)
+                return err;
 
+        set_current_blocked(&set);
         regs->bta       = uregs.scratch.bta;
         regs->lp_start  = uregs.scratch.lp_start;
         regs->lp_end    = uregs.scratch.lp_end;
@@ -138,7 +138,7 @@ static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
         regs->r0        = uregs.scratch.r0;
         regs->sp        = uregs.scratch.sp;
 
-        return err;
+        return 0;
 }
 
 static inline int is_do_ss_needed(unsigned int magic)
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
index a93c0f99acf7..1f59ea051bab 100644
--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -533,11 +533,12 @@ __clear_user(void __user *addr, unsigned long n)
 
 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
 {
-        if (access_ok(VERIFY_READ, from, n))
-                n = __copy_from_user(to, from, n);
-        else /* security hole - plug it */
-                memset(to, 0, n);
-        return n;
+        unsigned long res = n;
+        if (likely(access_ok(VERIFY_READ, from, n)))
+                res = __copy_from_user(to, from, n);
+        if (unlikely(res))
+                memset(to + (n - res), 0, res);
+        return res;
 }
 
 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
diff --git a/arch/arm/lib/copy_from_user.S b/arch/arm/lib/copy_from_user.S
index f549c57ea435..63e4c1ed0225 100644
--- a/arch/arm/lib/copy_from_user.S
+++ b/arch/arm/lib/copy_from_user.S
@@ -100,12 +100,9 @@ EXPORT_SYMBOL(arm_copy_from_user)
         .pushsection .fixup,"ax"
         .align 0
         copy_abort_preamble
-        ldmfd   sp!, {r1, r2}
-        sub     r3, r0, r1
-        rsb     r1, r3, r2
-        str     r1, [sp]
-        bl      __memzero
-        ldr     r0, [sp], #4
+        ldmfd   sp!, {r1, r2, r3}
+        sub     r0, r0, r1
+        rsb     r0, r0, r2
         copy_abort_end
         .popsection
 
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index c47257c91b77..bcaf6fba1b65 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -278,14 +278,16 @@ static inline unsigned long __must_check __copy_to_user(void __user *to, const v
 
 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
 {
+        unsigned long res = n;
         kasan_check_write(to, n);
 
         if (access_ok(VERIFY_READ, from, n)) {
                 check_object_size(to, n, false);
-                n = __arch_copy_from_user(to, from, n);
-        } else /* security hole - plug it */
-                memset(to, 0, n);
-        return n;
+                res = __arch_copy_from_user(to, from, n);
+        }
+        if (unlikely(res))
+                memset(to + (n - res), 0, res);
+        return res;
 }
 
 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S
index 0b90497d4424..4fd67ea03bb0 100644
--- a/arch/arm64/lib/copy_from_user.S
+++ b/arch/arm64/lib/copy_from_user.S
@@ -79,11 +79,6 @@ ENDPROC(__arch_copy_from_user)
 
         .section .fixup,"ax"
         .align  2
-9998:
-        sub     x0, end, dst
-9999:
-        strb    wzr, [dst], #1                  // zero remaining buffer space
-        cmp     dst, end
-        b.lo    9999b
+9998:   sub     x0, end, dst                    // bytes not copied
         ret
         .previous
diff --git a/arch/blackfin/include/asm/uaccess.h b/arch/blackfin/include/asm/uaccess.h
index 0a2a70096d8b..0eff88aa6d6a 100644
--- a/arch/blackfin/include/asm/uaccess.h
+++ b/arch/blackfin/include/asm/uaccess.h
@@ -163,18 +163,29 @@ static inline int bad_user_access_length(void)
                 : "a" (__ptr(ptr)));            \
 })
 
-#define __copy_from_user(to, from, n) copy_from_user(to, from, n)
-#define __copy_to_user(to, from, n) copy_to_user(to, from, n)
 #define __copy_to_user_inatomic __copy_to_user
 #define __copy_from_user_inatomic __copy_from_user
 
 static inline unsigned long __must_check
+__copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+        memcpy(to, (const void __force *)from, n);
+        return 0;
+}
+
+static inline unsigned long __must_check
+__copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+        memcpy((void __force *)to, from, n);
+        SSYNC();
+        return 0;
+}
+
+static inline unsigned long __must_check
 copy_from_user(void *to, const void __user *from, unsigned long n)
 {
-        if (likely(access_ok(VERIFY_READ, from, n))) {
-                memcpy(to, (const void __force *)from, n);
-                return 0;
-        }
+        if (likely(access_ok(VERIFY_READ, from, n)))
+                return __copy_from_user(to, from, n);
         memset(to, 0, n);
         return n;
 }
@@ -182,12 +193,9 @@ copy_from_user(void *to, const void __user *from, unsigned long n)
 static inline unsigned long __must_check
 copy_to_user(void __user *to, const void *from, unsigned long n)
 {
-        if (access_ok(VERIFY_WRITE, to, n))
-                memcpy((void __force *)to, from, n);
-        else
-                return n;
-        SSYNC();
-        return 0;
+        if (likely(access_ok(VERIFY_WRITE, to, n)))
+                return __copy_to_user(to, from, n);
+        return n;
 }
 
 /*
diff --git a/arch/score/kernel/traps.c b/arch/score/kernel/traps.c
index 1517a7dcd6d9..5cea1e750cec 100644
--- a/arch/score/kernel/traps.c
+++ b/arch/score/kernel/traps.c
@@ -29,6 +29,7 @@
 #include <asm/cacheflush.h>
 #include <asm/irq.h>
 #include <asm/irq_regs.h>
+#include <asm/uaccess.h>
 
 unsigned long exception_handlers[32];
 
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 89182c4e2e30..bcf3965be819 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1303,6 +1303,12 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
         if (!oe)
                 goto out_put_cred;
 
+        sb->s_magic = OVERLAYFS_SUPER_MAGIC;
+        sb->s_op = &ovl_super_operations;
+        sb->s_xattr = ovl_xattr_handlers;
+        sb->s_fs_info = ufs;
+        sb->s_flags |= MS_POSIXACL | MS_NOREMOTELOCK;
+
         root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR));
         if (!root_dentry)
                 goto out_free_oe;
@@ -1326,12 +1332,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
         ovl_inode_init(d_inode(root_dentry), realinode, !!upperpath.dentry);
         ovl_copyattr(realinode, d_inode(root_dentry));
 
-        sb->s_magic = OVERLAYFS_SUPER_MAGIC;
-        sb->s_op = &ovl_super_operations;
-        sb->s_xattr = ovl_xattr_handlers;
         sb->s_root = root_dentry;
-        sb->s_fs_info = ufs;
-        sb->s_flags |= MS_POSIXACL | MS_NOREMOTELOCK;
 
         return 0;
 
diff --git a/fs/read_write.c b/fs/read_write.c
index 66215a7b17cf..190e0d362581 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -730,6 +730,35 @@ static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
 /* A write operation does a read from user space and vice versa */
 #define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)
 
+/**
+ * rw_copy_check_uvector() - Copy an array of &struct iovec from userspace
+ *     into the kernel and check that it is valid.
+ *
+ * @type: One of %CHECK_IOVEC_ONLY, %READ, or %WRITE.
+ * @uvector: Pointer to the userspace array.
+ * @nr_segs: Number of elements in userspace array.
+ * @fast_segs: Number of elements in @fast_pointer.
+ * @fast_pointer: Pointer to (usually small on-stack) kernel array.
+ * @ret_pointer: (output parameter) Pointer to a variable that will point to
+ *     either @fast_pointer, a newly allocated kernel array, or NULL,
+ *     depending on which array was used.
+ *
+ * This function copies an array of &struct iovec of @nr_segs from
+ * userspace into the kernel and checks that each element is valid (e.g.
+ * it does not point to a kernel address or cause overflow by being too
+ * large, etc.).
+ *
+ * As an optimization, the caller may provide a pointer to a small
+ * on-stack array in @fast_pointer, typically %UIO_FASTIOV elements long
+ * (the size of this array, or 0 if unused, should be given in @fast_segs).
+ *
+ * @ret_pointer will always point to the array that was used, so the
+ * caller must take care not to call kfree() on it e.g. in case the
+ * @fast_pointer array was used and it was allocated on the stack.
+ *
+ * Return: The total number of bytes covered by the iovec array on success
+ *   or a negative error code on error.
+ */
 ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
                               unsigned long nr_segs, unsigned long fast_segs,
                               struct iovec *fast_pointer,
diff --git a/fs/super.c b/fs/super.c
index c2ff475c1711..c183835566c1 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1269,25 +1269,34 @@ EXPORT_SYMBOL(__sb_start_write);
 static void sb_wait_write(struct super_block *sb, int level)
 {
         percpu_down_write(sb->s_writers.rw_sem + level-1);
-        /*
-         * We are going to return to userspace and forget about this lock, the
-         * ownership goes to the caller of thaw_super() which does unlock.
-         *
-         * FIXME: we should do this before return from freeze_super() after we
-         * called sync_filesystem(sb) and s_op->freeze_fs(sb), and thaw_super()
-         * should re-acquire these locks before s_op->unfreeze_fs(sb). However
-         * this leads to lockdep false-positives, so currently we do the early
-         * release right after acquire.
-         */
-        percpu_rwsem_release(sb->s_writers.rw_sem + level-1, 0, _THIS_IP_);
 }
 
-static void sb_freeze_unlock(struct super_block *sb)
+/*
+ * We are going to return to userspace and forget about these locks, the
+ * ownership goes to the caller of thaw_super() which does unlock().
+ */
+static void lockdep_sb_freeze_release(struct super_block *sb)
+{
+        int level;
+
+        for (level = SB_FREEZE_LEVELS - 1; level >= 0; level--)
+                percpu_rwsem_release(sb->s_writers.rw_sem + level, 0, _THIS_IP_);
+}
+
+/*
+ * Tell lockdep we are holding these locks before we call ->unfreeze_fs(sb).
+ */
+static void lockdep_sb_freeze_acquire(struct super_block *sb)
 {
         int level;
 
         for (level = 0; level < SB_FREEZE_LEVELS; ++level)
                 percpu_rwsem_acquire(sb->s_writers.rw_sem + level, 0, _THIS_IP_);
+}
+
+static void sb_freeze_unlock(struct super_block *sb)
+{
+        int level;
 
         for (level = SB_FREEZE_LEVELS - 1; level >= 0; level--)
                 percpu_up_write(sb->s_writers.rw_sem + level);
@@ -1379,10 +1388,11 @@ int freeze_super(struct super_block *sb)
                 }
         }
         /*
-         * This is just for debugging purposes so that fs can warn if it
-         * sees write activity when frozen is set to SB_FREEZE_COMPLETE.
+         * For debugging purposes so that fs can warn if it sees write activity
+         * when frozen is set to SB_FREEZE_COMPLETE, and for thaw_super().
          */
         sb->s_writers.frozen = SB_FREEZE_COMPLETE;
+        lockdep_sb_freeze_release(sb);
         up_write(&sb->s_umount);
         return 0;
 }
@@ -1399,7 +1409,7 @@ int thaw_super(struct super_block *sb)
         int error;
 
         down_write(&sb->s_umount);
-        if (sb->s_writers.frozen == SB_UNFROZEN) {
+        if (sb->s_writers.frozen != SB_FREEZE_COMPLETE) {
                 up_write(&sb->s_umount);
                 return -EINVAL;
         }
@@ -1409,11 +1419,14 @@ int thaw_super(struct super_block *sb)
                 goto out;
         }
 
+        lockdep_sb_freeze_acquire(sb);
+
         if (sb->s_op->unfreeze_fs) {
                 error = sb->s_op->unfreeze_fs(sb);
                 if (error) {
                         printk(KERN_ERR
                                 "VFS:Filesystem thaw failed\n");
+                        lockdep_sb_freeze_release(sb);
                         up_write(&sb->s_umount);
                         return error;
                 }
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 7312e7784611..f0c7f1481bae 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1139,6 +1139,28 @@ const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
 }
 EXPORT_SYMBOL(dup_iter);
 
+/**
+ * import_iovec() - Copy an array of &struct iovec from userspace
+ *     into the kernel, check that it is valid, and initialize a new
+ *     &struct iov_iter iterator to access it.
+ *
+ * @type: One of %READ or %WRITE.
+ * @uvector: Pointer to the userspace array.
+ * @nr_segs: Number of elements in userspace array.
+ * @fast_segs: Number of elements in @iov.
+ * @iov: (input and output parameter) Pointer to pointer to (usually small
+ *     on-stack) kernel array.
+ * @i: Pointer to iterator that will be initialized on success.
+ *
+ * If the array pointed to by *@iov is large enough to hold all @nr_segs,
+ * then this function places %NULL in *@iov on return. Otherwise, a new
+ * array will be allocated and the result placed in *@iov. This means that
+ * the caller may call kfree() on *@iov regardless of whether the small
+ * on-stack array was used or not (and regardless of whether this function
+ * returns an error or not).
+ *
+ * Return: 0 on success or negative error code on error.
+ */
 int import_iovec(int type, const struct iovec __user * uvector,
                  unsigned nr_segs, unsigned fast_segs,
                  struct iovec **iov, struct iov_iter *i)