1 files changed, 59 insertions, 36 deletions

diff --git a/fs/read_write.c b/fs/read_write.c
index 74e36586e4d3..431a0ed610c8 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -31,6 +31,20 @@ const struct file_operations generic_ro_fops = {
 
 EXPORT_SYMBOL(generic_ro_fops);
 
+static int
+__negative_fpos_check(struct file *file, loff_t pos, size_t count)
+{
+        /*
+         * pos or pos+count is negative here, check overflow.
+         * too big "count" will be caught in rw_verify_area().
+         */
+        if ((pos < 0) && (pos + count < pos))
+                return -EOVERFLOW;
+        if (file->f_mode & FMODE_UNSIGNED_OFFSET)
+                return 0;
+        return -EINVAL;
+}
+
 /**
  * generic_file_llseek_unlocked - lockless generic llseek implementation
  * @file:       file structure to seek on
@@ -62,7 +76,9 @@ generic_file_llseek_unlocked(struct file *file, loff_t offset, int origin)
                 break;
         }
 
-        if (offset < 0 || offset > inode->i_sb->s_maxbytes)
+        if (offset < 0 && __negative_fpos_check(file, offset, 0))
+                return -EINVAL;
+        if (offset > inode->i_sb->s_maxbytes)
                 return -EINVAL;
 
         /* Special lock needed here? */
@@ -124,7 +140,7 @@ loff_t default_llseek(struct file *file, loff_t offset, int origin)
 {
         loff_t retval;
 
-        lock_kernel();
+        mutex_lock(&file->f_dentry->d_inode->i_mutex);
         switch (origin) {
                 case SEEK_END:
                         offset += i_size_read(file->f_path.dentry->d_inode);
@@ -137,7 +153,7 @@ loff_t default_llseek(struct file *file, loff_t offset, int origin)
                         offset += file->f_pos;
         }
         retval = -EINVAL;
-        if (offset >= 0) {
+        if (offset >= 0 || !__negative_fpos_check(file, offset, 0)) {
                 if (offset != file->f_pos) {
                         file->f_pos = offset;
                         file->f_version = 0;
@@ -145,7 +161,7 @@ loff_t default_llseek(struct file *file, loff_t offset, int origin)
                 retval = offset;
         }
 out:
-        unlock_kernel();
+        mutex_unlock(&file->f_dentry->d_inode->i_mutex);
         return retval;
 }
 EXPORT_SYMBOL(default_llseek);
@@ -156,7 +172,6 @@ loff_t vfs_llseek(struct file *file, loff_t offset, int origin)
 
         fn = no_llseek;
         if (file->f_mode & FMODE_LSEEK) {
-                fn = default_llseek;
                 if (file->f_op && file->f_op->llseek)
                         fn = file->f_op->llseek;
         }
@@ -222,13 +237,12 @@ bad:
 }
 #endif
 
+
 /*
  * rw_verify_area doesn't like huge counts. We limit
  * them to something that fits in "int" so that others
  * won't have to do range checks all the time.
  */
-#define MAX_RW_COUNT (INT_MAX & PAGE_CACHE_MASK)
-
 int rw_verify_area(int read_write, struct file *file, loff_t *ppos, size_t count)
 {
         struct inode *inode;
@@ -239,8 +253,11 @@ int rw_verify_area(int read_write, struct file *file, loff_t *ppos, size_t count
         if (unlikely((ssize_t) count < 0))
                 return retval;
         pos = *ppos;
-        if (unlikely((pos < 0) || (loff_t) (pos + count) < 0))
-                return retval;
+        if (unlikely((pos < 0) || (loff_t) (pos + count) < 0)) {
+                retval = __negative_fpos_check(file, pos, count);
+                if (retval)
+                        return retval;
+        }
 
         if (unlikely(inode->i_flock && mandatory_lock(inode))) {
                 retval = locks_mandatory_area(
@@ -565,65 +582,71 @@ 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,
                               struct iovec **ret_pointer)
-  {
+{
         unsigned long seg;
-        ssize_t ret;
+        ssize_t ret;
         struct iovec *iov = fast_pointer;
 
-        /*
-         * SuS says "The readv() function *may* fail if the iovcnt argument
-         * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
-         * traditionally returned zero for zero segments, so...
-         */
+        /*
+         * SuS says "The readv() function *may* fail if the iovcnt argument
+         * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
+         * traditionally returned zero for zero segments, so...
+         */
         if (nr_segs == 0) {
                 ret = 0;
-                goto out;
+                goto out;
         }
 
-        /*
-         * First get the "struct iovec" from user memory and
-         * verify all the pointers
-         */
+        /*
+         * First get the "struct iovec" from user memory and
+         * verify all the pointers
+         */
         if (nr_segs > UIO_MAXIOV) {
                 ret = -EINVAL;
-                goto out;
+                goto out;
         }
         if (nr_segs > fast_segs) {
-                iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
+                iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
                 if (iov == NULL) {
                         ret = -ENOMEM;
-                        goto out;
+                        goto out;
                 }
-        }
+        }
         if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector))) {
                 ret = -EFAULT;
-                goto out;
+                goto out;
         }
 
-        /*
+        /*
          * According to the Single Unix Specification we should return EINVAL
          * if an element length is < 0 when cast to ssize_t or if the
          * total length would overflow the ssize_t return value of the
          * system call.
-         */
+         *
+         * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the
+         * overflow case.
+         */
         ret = 0;
-        for (seg = 0; seg < nr_segs; seg++) {
-                void __user *buf = iov[seg].iov_base;
-                ssize_t len = (ssize_t)iov[seg].iov_len;
+        for (seg = 0; seg < nr_segs; seg++) {
+                void __user *buf = iov[seg].iov_base;
+                ssize_t len = (ssize_t)iov[seg].iov_len;
 
                 /* see if we we're about to use an invalid len or if
                  * it's about to overflow ssize_t */
-                if (len < 0 || (ret + len < ret)) {
+                if (len < 0) {
                         ret = -EINVAL;
-                        goto out;
+                        goto out;
                 }
                 if (unlikely(!access_ok(vrfy_dir(type), buf, len))) {
                         ret = -EFAULT;
-                        goto out;
+                        goto out;
+                }
+                if (len > MAX_RW_COUNT - ret) {
+                        len = MAX_RW_COUNT - ret;
+                        iov[seg].iov_len = len;
                 }
-
                 ret += len;
-        }
+        }
 out:
         *ret_pointer = iov;
         return ret;