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authorMichel Lespinasse <walken@google.com>2013-03-14 16:50:02 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-03-14 17:00:39 -0700
commita2362d24764a4e9a3187fc46b14e1d2cd0657700 (patch)
treeb4b067886ae9a6f7cc8bff96ab2f7096b1f493aa /mm/fremap.c
parentf4846e52c51755fe1dd6642a117bc23cd0655c95 (diff)
downloadlinux-a2362d24764a4e9a3187fc46b14e1d2cd0657700.tar.gz
mm/fremap.c: fix possible oops on error path
The vm_flags introduced in 6d7825b10dbe ("mm/fremap.c: fix oops on error path") is supposed to avoid a compiler warning about unitialized vm_flags without changing the generated code. However I am concerned that this is going to be very brittle, and fail with some compiler versions. The failure could be either of: - compiler could actually load vma->vm_flags before checking for the !vma condition, thus reintroducing the oops - compiler could optimize out the !vma check, since the pointer just got dereferenced shortly before (so the compiler knows it can't be NULL!) I propose reversing this part of the change and initializing vm_flags to 0 just to avoid the bogus uninitialized use warning. Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Tommi Rantala <tt.rantala@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/fremap.c')
-rw-r--r--mm/fremap.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/mm/fremap.c b/mm/fremap.c
index 6a8da7ee85f..4723ac8d2fc 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -129,7 +129,7 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
struct vm_area_struct *vma;
int err = -EINVAL;
int has_write_lock = 0;
- vm_flags_t vm_flags;
+ vm_flags_t vm_flags = 0;
if (prot)
return err;
@@ -163,8 +163,7 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
* and that the remapped range is valid and fully within
* the single existing vma.
*/
- vm_flags = vma->vm_flags;
- if (!vma || !(vm_flags & VM_SHARED))
+ if (!vma || !(vma->vm_flags & VM_SHARED))
goto out;
if (!vma->vm_ops || !vma->vm_ops->remap_pages)