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From ba51b041eea7da8faf955770092d6f6ba7f21037 Mon Sep 17 00:00:00 2001
From: Stefano Garzarella <sgarzare@redhat.com>
Date: Fri, 10 Sep 2021 14:45:33 +0200
Subject: [PATCH 2/3] block/mirror: fix NULL pointer dereference in
mirror_wait_on_conflicts()
In mirror_iteration() we call mirror_wait_on_conflicts() with
`self` parameter set to NULL.
Starting from commit d44dae1a7c we dereference `self` pointer in
mirror_wait_on_conflicts() without checks if it is not NULL.
Backtrace:
Program terminated with signal SIGSEGV, Segmentation fault.
#0 mirror_wait_on_conflicts (self=0x0, s=<optimized out>, offset=<optimized out>, bytes=<optimized out>)
at ../block/mirror.c:172
172 self->waiting_for_op = op;
[Current thread is 1 (Thread 0x7f0908931ec0 (LWP 380249))]
(gdb) bt
#0 mirror_wait_on_conflicts (self=0x0, s=<optimized out>, offset=<optimized out>, bytes=<optimized out>)
at ../block/mirror.c:172
#1 0x00005610c5d9d631 in mirror_run (job=0x5610c76a2c00, errp=<optimized out>) at ../block/mirror.c:491
#2 0x00005610c5d58726 in job_co_entry (opaque=0x5610c76a2c00) at ../job.c:917
#3 0x00005610c5f046c6 in coroutine_trampoline (i0=<optimized out>, i1=<optimized out>)
at ../util/coroutine-ucontext.c:173
#4 0x00007f0909975820 in ?? () at ../sysdeps/unix/sysv/linux/x86_64/__start_context.S:91
from /usr/lib64/libc.so.6
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2001404
Fixes: d44dae1a7c ("block/mirror: fix active mirror dead-lock in mirror_wait_on_conflicts")
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20210910124533.288318-1-sgarzare@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Upstream-Status: Backport [66fed30c9cd11854fc878a4eceb507e915d7c9cd]
Signed-off-by: Sakib Sajal <sakib.sajal@windriver.com>
---
block/mirror.c | 25 ++++++++++++++++---------
1 file changed, 16 insertions(+), 9 deletions(-)
diff --git a/block/mirror.c b/block/mirror.c
index fab008568..ca0be146f 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -159,18 +159,25 @@ static void coroutine_fn mirror_wait_on_conflicts(MirrorOp *self,
if (ranges_overlap(self_start_chunk, self_nb_chunks,
op_start_chunk, op_nb_chunks))
{
- /*
- * If the operation is already (indirectly) waiting for us, or
- * will wait for us as soon as it wakes up, then just go on
- * (instead of producing a deadlock in the former case).
- */
- if (op->waiting_for_op) {
- continue;
+ if (self) {
+ /*
+ * If the operation is already (indirectly) waiting for us,
+ * or will wait for us as soon as it wakes up, then just go
+ * on (instead of producing a deadlock in the former case).
+ */
+ if (op->waiting_for_op) {
+ continue;
+ }
+
+ self->waiting_for_op = op;
}
- self->waiting_for_op = op;
qemu_co_queue_wait(&op->waiting_requests, NULL);
- self->waiting_for_op = NULL;
+
+ if (self) {
+ self->waiting_for_op = NULL;
+ }
+
break;
}
}
--
2.33.0
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