NFSD: memory corruption due to writing beyond the stat array
If nfsd fails to find an exported via NFS file in the readahead cache, it
should increment corresponding nfsdstats counter (ra_depth[10]), but due to a
bug it may instead write to ra_depth[11], corrupting the following field.
In a kernel with NFSDv4 compiled in the corruption takes the form of an
increment of a counter of the number of NFSv4 operation 0's received; since
there is no operation 0, this is harmless.
In a kernel with NFSDv4 disabled it corrupts whatever happens to be in the
memory beyond nfsdstats.
Signed-off-by: Konstantin Khorenko <khorenko@openvz.org>
Cc: stable@kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index fda3be2..30c73f8 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -808,7 +808,7 @@
if (ra->p_count == 0)
frap = rap;
}
- depth = nfsdstats.ra_size*11/10;
+ depth = nfsdstats.ra_size;
if (!frap) {
spin_unlock(&rab->pb_lock);
return NULL;