From cc0f678353027580c09748ef15e0183a37745291 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Mon, 8 Jun 2020 16:48:43 +1000 Subject: crypto: af_alg - fix use-after-free in af_alg_accept() due to bh_lock_sock() commit 34c86f4c4a7be3b3e35aa48bd18299d4c756064d upstream. The locking in af_alg_release_parent is broken as the BH socket lock can only be taken if there is a code-path to handle the case where the lock is owned by process-context. Instead of adding such handling, we can fix this by changing the ref counts to atomic_t. This patch also modifies the main refcnt to include both normal and nokey sockets. This way we don't have to fudge the nokey ref count when a socket changes from nokey to normal. Credits go to Mauricio Faria de Oliveira who diagnosed this bug and sent a patch for it: https://lore.kernel.org/linux-crypto/20200605161657.535043-1-mfo@canonical.com/ Reported-by: Brian Moyles Reported-by: Mauricio Faria de Oliveira Fixes: 37f96694cf73 ("crypto: af_alg - Use bh_lock_sock in...") Cc: Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman --- include/crypto/if_alg.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/crypto') diff --git a/include/crypto/if_alg.h b/include/crypto/if_alg.h index 24cfa96f98ea..864849e942c4 100644 --- a/include/crypto/if_alg.h +++ b/include/crypto/if_alg.h @@ -29,8 +29,8 @@ struct alg_sock { struct sock *parent; - unsigned int refcnt; - unsigned int nokey_refcnt; + atomic_t refcnt; + atomic_t nokey_refcnt; const struct af_alg_type *type; void *private; -- cgit v1.2.3