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authorJan Kara <jack@suse.cz>2019-12-16 11:54:32 +0100
committerAl Viro <viro@zeniv.linux.org.uk>2019-12-16 12:48:10 -0500
commite0ff126ee7ad405c1ef531f9f3db92929de4f20f (patch)
tree3db8cda1843d84196659155c7690644449d2bc18 /lib/iov_iter.c
parente42617b825f8073569da76dc4510bfa019b1c35a (diff)
downloadlinux-e0ff126ee7ad405c1ef531f9f3db92929de4f20f.tar.bz2
pipe: Fix bogus dereference in iov_iter_alignment()
We cannot look at 'i->pipe' unless we know the iter is a pipe. Move the ring_size load to a branch in iov_iter_alignment() where we've already checked the iter is a pipe to avoid bogus dereference. Reported-by: syzbot+bea68382bae9490e7dd6@syzkaller.appspotmail.com Fixes: 8cefc107ca54 ("pipe: Use head and tail pointers for the ring, not cursor and length") Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'lib/iov_iter.c')
-rw-r--r--lib/iov_iter.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index fb29c02c6a3c..51595bf3af85 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1222,11 +1222,12 @@ EXPORT_SYMBOL(iov_iter_discard);
unsigned long iov_iter_alignment(const struct iov_iter *i)
{
- unsigned int p_mask = i->pipe->ring_size - 1;
unsigned long res = 0;
size_t size = i->count;
if (unlikely(iov_iter_is_pipe(i))) {
+ unsigned int p_mask = i->pipe->ring_size - 1;
+
if (size && i->iov_offset && allocated(&i->pipe->bufs[i->head & p_mask]))
return size | i->iov_offset;
return size;