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authorRasmus Villemoes <linux@rasmusvillemoes.dk>2013-04-29 15:08:23 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-04-29 15:54:37 -0700
commit84d96d897671cfb386e722acbefdb3a79e115a8a (patch)
tree0d7559bf9434ccfd933cfd385ff2c3843e6fd396 /mm
parent4edd7ceff0662afde195da6f6c43e7cbe1ed2dc4 (diff)
downloadlinux-84d96d897671cfb386e722acbefdb3a79e115a8a.tar.gz
mm: madvise: complete input validation before taking lock
In madvise(), there doesn't seem to be any reason for taking the &current->mm->mmap_sem before start and len_in have been validated. Incidentally, this removes the need for the out: label. [akpm@linux-foundation.org: s/out_plug/out/, per David] Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/madvise.c31
1 files changed, 15 insertions, 16 deletions
diff --git a/mm/madvise.c b/mm/madvise.c
index c58c94b56c3..7055883e6e2 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -473,27 +473,27 @@ SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
if (!madvise_behavior_valid(behavior))
return error;
- write = madvise_need_mmap_write(behavior);
- if (write)
- down_write(&current->mm->mmap_sem);
- else
- down_read(&current->mm->mmap_sem);
-
if (start & ~PAGE_MASK)
- goto out;
+ return error;
len = (len_in + ~PAGE_MASK) & PAGE_MASK;
/* Check to see whether len was rounded up from small -ve to zero */
if (len_in && !len)
- goto out;
+ return error;
end = start + len;
if (end < start)
- goto out;
+ return error;
error = 0;
if (end == start)
- goto out;
+ return error;
+
+ write = madvise_need_mmap_write(behavior);
+ if (write)
+ down_write(&current->mm->mmap_sem);
+ else
+ down_read(&current->mm->mmap_sem);
/*
* If the interval [start,end) covers some unmapped address
@@ -509,14 +509,14 @@ SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
/* Still start < end. */
error = -ENOMEM;
if (!vma)
- goto out_plug;
+ goto out;
/* Here start < (end|vma->vm_end). */
if (start < vma->vm_start) {
unmapped_error = -ENOMEM;
start = vma->vm_start;
if (start >= end)
- goto out_plug;
+ goto out;
}
/* Here vma->vm_start <= start < (end|vma->vm_end) */
@@ -527,21 +527,20 @@ SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
/* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
error = madvise_vma(vma, &prev, start, tmp, behavior);
if (error)
- goto out_plug;
+ goto out;
start = tmp;
if (prev && start < prev->vm_end)
start = prev->vm_end;
error = unmapped_error;
if (start >= end)
- goto out_plug;
+ goto out;
if (prev)
vma = prev->vm_next;
else /* madvise_remove dropped mmap_sem */
vma = find_vma(current->mm, start);
}
-out_plug:
- blk_finish_plug(&plug);
out:
+ blk_finish_plug(&plug);
if (write)
up_write(&current->mm->mmap_sem);
else