From: Paolo Bonzini <pbonzini@redhat.com>
Date: Tue, 26 Jun 2018 13:39:18 +0000 (+0200)
Subject: pr-manager-helper: avoid SIGSEGV when writing to the socket fail
X-Git-Tag: pull-nvme-20200902~1642^2~26
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=aad10040d411d21542dc9ae58a2854c89ccedd78;p=qemu-nvme.git

pr-manager-helper: avoid SIGSEGV when writing to the socket fail

When writing to the qemu-pr-helper socket failed, the persistent
reservation manager was correctly disconnecting the socket, but it
did not clear pr_mgr->ioc.  So the rest of the code did not know
that the socket had been disconnected, accessed pr_mgr->ioc and
happily caused a crash.

To reproduce, it is enough to stop qemu-pr-helper between QEMU
startup and executing e.g. sg_persist -k /dev/sdb.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---

diff --git a/scsi/pr-manager-helper.c b/scsi/pr-manager-helper.c
index 82ff6b6123..0c0fe389b7 100644
--- a/scsi/pr-manager-helper.c
+++ b/scsi/pr-manager-helper.c
@@ -71,6 +71,7 @@ static int pr_manager_helper_write(PRManagerHelper *pr_mgr,
         if (n_written <= 0) {
             assert(n_written != QIO_CHANNEL_ERR_BLOCK);
             object_unref(OBJECT(pr_mgr->ioc));
+            pr_mgr->ioc = NULL;
             return n_written < 0 ? -EINVAL : 0;
         }