From: Greg Kroah-Hartman Date: Tue, 23 Jun 2020 12:24:01 +0000 (+0200) Subject: 4.4-stable patches X-Git-Tag: v5.7.6~19 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=5aaf63b28afc39e0b261a3cb16f1ae977329b232;p=thirdparty%2Fkernel%2Fstable-queue.git 4.4-stable patches added patches: crypto-algboss-don-t-wait-during-notifier-callback.patch --- diff --git a/queue-4.4/crypto-algboss-don-t-wait-during-notifier-callback.patch b/queue-4.4/crypto-algboss-don-t-wait-during-notifier-callback.patch new file mode 100644 index 00000000000..88e532d28e8 --- /dev/null +++ b/queue-4.4/crypto-algboss-don-t-wait-during-notifier-callback.patch @@ -0,0 +1,58 @@ +From 77251e41f89a813b4090f5199442f217bbf11297 Mon Sep 17 00:00:00 2001 +From: Eric Biggers +Date: Thu, 4 Jun 2020 11:52:53 -0700 +Subject: crypto: algboss - don't wait during notifier callback +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +From: Eric Biggers + +commit 77251e41f89a813b4090f5199442f217bbf11297 upstream. + +When a crypto template needs to be instantiated, CRYPTO_MSG_ALG_REQUEST +is sent to crypto_chain. cryptomgr_schedule_probe() handles this by +starting a thread to instantiate the template, then waiting for this +thread to complete via crypto_larval::completion. + +This can deadlock because instantiating the template may require loading +modules, and this (apparently depending on userspace) may need to wait +for the crc-t10dif module (lib/crc-t10dif.c) to be loaded. But +crc-t10dif's module_init function uses crypto_register_notifier() and +therefore takes crypto_chain.rwsem for write. That can't proceed until +the notifier callback has finished, as it holds this semaphore for read. + +Fix this by removing the wait on crypto_larval::completion from within +cryptomgr_schedule_probe(). It's actually unnecessary because +crypto_alg_mod_lookup() calls crypto_larval_wait() itself after sending +CRYPTO_MSG_ALG_REQUEST. + +This only actually became a problem in v4.20 due to commit b76377543b73 +("crc-t10dif: Pick better transform if one becomes available"), but the +unnecessary wait was much older. + +BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=207159 +Reported-by: Mike Gerow +Fixes: 398710379f51 ("crypto: algapi - Move larval completion into algboss") +Cc: # v3.6+ +Cc: Martin K. Petersen +Signed-off-by: Eric Biggers +Reported-by: Kai Lüke +Signed-off-by: Herbert Xu +Signed-off-by: Greg Kroah-Hartman + +--- + crypto/algboss.c | 2 -- + 1 file changed, 2 deletions(-) + +--- a/crypto/algboss.c ++++ b/crypto/algboss.c +@@ -194,8 +194,6 @@ static int cryptomgr_schedule_probe(stru + if (IS_ERR(thread)) + goto err_put_larval; + +- wait_for_completion_interruptible(&larval->completion); +- + return NOTIFY_STOP; + + err_put_larval: diff --git a/queue-4.4/series b/queue-4.4/series index 76a5f91143f..415316afb8e 100644 --- a/queue-4.4/series +++ b/queue-4.4/series @@ -68,3 +68,4 @@ ext4-fix-partial-cluster-initialization-when-splitti.patch drm-dp_mst-increase-act-retry-timeout-to-3s.patch sparc64-fix-misuses-of-access_process_vm-in-genregs3.patch block-nr_sects_write-disable-preemption-on-seqcount-.patch +crypto-algboss-don-t-wait-during-notifier-callback.patch