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authorDavid Howells <dhowells@redhat.com>2023-06-15 22:08:54 +0100
committerDavid S. Miller <davem@davemloft.net>2023-06-18 14:26:21 +0100
commit4380499218c6a1aa77e80e3bf6da107dd8babf62 (patch)
treed0f155b2c2f6cd18064fd63f8b7ce17ca7b859c7 /crypto/af_alg.c
parent7a7f094635349a7d0314364ad50bdeb770b6df4f (diff)
crypto: Fix af_alg_sendmsg(MSG_SPLICE_PAGES) sglist limit
When af_alg_sendmsg() calls extract_iter_to_sg(), it passes MAX_SGL_ENTS as the maximum number of elements that may be written to, but some of the elements may already have been used (as recorded in sgl->cur), so extract_iter_to_sg() may end up overrunning the scatterlist. Fix this to limit the number of elements to "MAX_SGL_ENTS - sgl->cur". Note: It probably makes sense in future to alter the behaviour of extract_iter_to_sg() to stop if "sgtable->nents >= sg_max" instead, but this is a smaller fix for now. The bug causes errors looking something like: BUG: KASAN: slab-out-of-bounds in sg_assign_page include/linux/scatterlist.h:109 [inline] BUG: KASAN: slab-out-of-bounds in sg_set_page include/linux/scatterlist.h:139 [inline] BUG: KASAN: slab-out-of-bounds in extract_bvec_to_sg lib/scatterlist.c:1183 [inline] BUG: KASAN: slab-out-of-bounds in extract_iter_to_sg lib/scatterlist.c:1352 [inline] BUG: KASAN: slab-out-of-bounds in extract_iter_to_sg+0x17a6/0x1960 lib/scatterlist.c:1339 Fixes: bf63e250c4b1 ("crypto: af_alg: Support MSG_SPLICE_PAGES") Reported-by: syzbot+6efc50cc1f8d718d6cb7@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/000000000000b2585a05fdeb8379@google.com/ Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: syzbot+6efc50cc1f8d718d6cb7@syzkaller.appspotmail.com cc: Herbert Xu <herbert@gondor.apana.org.au> cc: "David S. Miller" <davem@davemloft.net> cc: Eric Dumazet <edumazet@google.com> cc: Jakub Kicinski <kuba@kernel.org> cc: Paolo Abeni <pabeni@redhat.com> cc: Jens Axboe <axboe@kernel.dk> cc: Matthew Wilcox <willy@infradead.org> cc: linux-crypto@vger.kernel.org cc: netdev@vger.kernel.org Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'crypto/af_alg.c')
-rw-r--r--crypto/af_alg.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 7d4b6016b83d..cdb1dcc5dd1a 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -1043,7 +1043,7 @@ int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,
};
plen = extract_iter_to_sg(&msg->msg_iter, len, &sgtable,
- MAX_SGL_ENTS, 0);
+ MAX_SGL_ENTS - sgl->cur, 0);
if (plen < 0) {
err = plen;
goto unlock;