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authorJohannes Thumshirn <jthumshirn@suse.de>2017-01-31 10:16:00 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-19 09:49:15 -0800
commitfd3fc0b4d7305fa7246622dcc0dec69c42443f45 (patch)
treef66560ae05fd7b68c20b687d4f08981eb810ab80
parent00ea1ceebe0d9f2dc1cc2b7bd575a00100c27869 (diff)
downloadlinux-stericsson-fd3fc0b4d7305fa7246622dcc0dec69c42443f45.tar.gz
scsi: don't BUG_ON() empty DMA transfers
Don't crash the machine just because of an empty transfer. Use WARN_ON() combined with returning an error. Found by Dmitry Vyukov and syzkaller. [ Changed to "WARN_ON_ONCE()". Al has a patch that should fix the root cause, but a BUG_ON() is not acceptable in any case, and a WARN_ON() might still be a cause of excessive log spamming. NOTE! If this warning ever triggers, we may end up leaking resources, since this doesn't bother to try to clean the command up. So this WARN_ON_ONCE() triggering does imply real problems. But BUG_ON() is much worse. People really need to stop using BUG_ON() for "this shouldn't ever happen". It makes pretty much any bug worse. - Linus ] Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de> Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: James Bottomley <jejb@linux.vnet.ibm.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--drivers/scsi/scsi_lib.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index e9e1e141af9c..78db07fd8055 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1040,7 +1040,8 @@ int scsi_init_io(struct scsi_cmnd *cmd)
bool is_mq = (rq->mq_ctx != NULL);
int error;
- BUG_ON(!blk_rq_nr_phys_segments(rq));
+ if (WARN_ON_ONCE(!blk_rq_nr_phys_segments(rq)))
+ return -EINVAL;
error = scsi_init_sgtable(rq, &cmd->sdb);
if (error)