relay: fix for possible loss/corruption of produced subbufs
Fix possible loss/corruption of produced subbufs in
relay_subbufs_consumed().
When buf->subbufs_produced wraps around after UINT_MAX and
buf->subbufs_consumed is still < UINT_MAX, the condition
if (buf->subbufs_consumed > buf->subbufs_produced)
will be true even for certain valid values of subbufs_consumed. This may
lead to loss or corruption of produced subbufs.
Signed-off-by: Aravind Srinivasan <raa.aars@gmail.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Tom Zanussi <zanussi@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/relay.c b/kernel/relay.c
index 8f2179c..e92db8c 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -797,13 +797,15 @@
if (!chan)
return;
- if (cpu >= NR_CPUS || !chan->buf[cpu])
+ if (cpu >= NR_CPUS || !chan->buf[cpu] ||
+ subbufs_consumed > chan->n_subbufs)
return;
buf = chan->buf[cpu];
- buf->subbufs_consumed += subbufs_consumed;
- if (buf->subbufs_consumed > buf->subbufs_produced)
+ if (subbufs_consumed > buf->subbufs_produced - buf->subbufs_consumed)
buf->subbufs_consumed = buf->subbufs_produced;
+ else
+ buf->subbufs_consumed += subbufs_consumed;
}
EXPORT_SYMBOL_GPL(relay_subbufs_consumed);