* [PATCH] block: bio_map_user_iov should not be limited to BIO_MAX_PAGES
@ 2019-04-17 11:50 Paolo Bonzini
0 siblings, 0 replies; only message in thread
From: Paolo Bonzini @ 2019-04-17 11:50 UTC (permalink / raw)
To: linux-kernel; +Cc: stefanha, stable, Al Viro, Jens Axboe, open list:BLOCK LAYER
Because bio_kmalloc uses inline iovecs, the limit on the number of entries
is not BIO_MAX_PAGES but rather UIO_MAX_IOV, which indeed is already checked
in bio_kmalloc. This could cause SG_IO requests to be truncated and the HBA
to report a DMA overrun.
Note that if the argument to iov_iter_npages were changed to UIO_MAX_IOV,
we would still truncate SG_IO requests beyond UIO_MAX_IOV pages. Changing
it to UIO_MAX_IOV + 1 instead ensures that bio_kmalloc notices that the
request is too big and blocks it.
Cc: stable@vger.kernel.org
Cc: Al Viro <viro@zeniv.linux.org.uk>
Fixes: b282cc766958 ("bio_map_user_iov(): get rid of the iov_for_each()", 2017-10-11)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
block/bio.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/bio.c b/block/bio.c
index 4db1008309ed..cc1195f5af7a 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1299,7 +1299,7 @@ struct bio *bio_map_user_iov(struct request_queue *q,
if (!iov_iter_count(iter))
return ERR_PTR(-EINVAL);
- bio = bio_kmalloc(gfp_mask, iov_iter_npages(iter, BIO_MAX_PAGES));
+ bio = bio_kmalloc(gfp_mask, iov_iter_npages(iter, UIO_MAX_IOV + 1));
if (!bio)
return ERR_PTR(-ENOMEM);
--
2.21.0
^ permalink raw reply related [flat|nested] only message in thread
only message in thread, other threads:[~2019-04-17 11:50 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-04-17 11:50 [PATCH] block: bio_map_user_iov should not be limited to BIO_MAX_PAGES Paolo Bonzini
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).