coredump: prevent double-free on an error path in core dumper

In !CORE_DUMP_USE_REGSET case, if elf_note_info_init fails to allocate
memory for info->fields, it frees already allocated stuff and returns
error to its caller, fill_note_info.  Which in turn returns error to its
caller, elf_core_dump.  Which jumps to cleanup label and calls
free_note_info, which will happily try to free all info->fields again.
BOOM.

This is the fix.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Venu Byravarasu <vbyravarasu@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 4 insertions, 15 deletions

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 1b52956afe33..0225fddf49b7 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1696,30 +1696,19 @@ static int elf_note_info_init(struct elf_note_info *info)
                 return 0;
         info->psinfo = kmalloc(sizeof(*info->psinfo), GFP_KERNEL);
         if (!info->psinfo)
-                goto notes_free;
+                return 0;
         info->prstatus = kmalloc(sizeof(*info->prstatus), GFP_KERNEL);
         if (!info->prstatus)
-                goto psinfo_free;
+                return 0;
         info->fpu = kmalloc(sizeof(*info->fpu), GFP_KERNEL);
         if (!info->fpu)
-                goto prstatus_free;
+                return 0;
 #ifdef ELF_CORE_COPY_XFPREGS
         info->xfpu = kmalloc(sizeof(*info->xfpu), GFP_KERNEL);
         if (!info->xfpu)
-                goto fpu_free;
+                return 0;
 #endif
         return 1;
-#ifdef ELF_CORE_COPY_XFPREGS
- fpu_free:
-        kfree(info->fpu);
-#endif
- prstatus_free:
-        kfree(info->prstatus);
- psinfo_free:
-        kfree(info->psinfo);
- notes_free:
-        kfree(info->notes);
-        return 0;
 }
 
 static int fill_note_info(struct elfhdr *elf, int phdrs,