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			84 lines
		
	
	
		
			3.6 KiB
		
	
	
	
		
			Diff
		
	
	
	
	
	
			
		
		
	
	
			84 lines
		
	
	
		
			3.6 KiB
		
	
	
	
		
			Diff
		
	
	
	
	
	
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Stefano Garzarella <sgarzare@redhat.com>
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Date: Fri, 10 Sep 2021 14:45:33 +0200
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Subject: [PATCH] block/mirror: fix NULL pointer dereference in
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 mirror_wait_on_conflicts()
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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In mirror_iteration() we call mirror_wait_on_conflicts() with
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`self` parameter set to NULL.
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Starting from commit d44dae1a7c we dereference `self` pointer in
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mirror_wait_on_conflicts() without checks if it is not NULL.
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Backtrace:
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  Program terminated with signal SIGSEGV, Segmentation fault.
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  #0  mirror_wait_on_conflicts (self=0x0, s=<optimized out>, offset=<optimized out>, bytes=<optimized out>)
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      at ../block/mirror.c:172
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  172	                self->waiting_for_op = op;
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  [Current thread is 1 (Thread 0x7f0908931ec0 (LWP 380249))]
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  (gdb) bt
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  #0  mirror_wait_on_conflicts (self=0x0, s=<optimized out>, offset=<optimized out>, bytes=<optimized out>)
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      at ../block/mirror.c:172
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  #1  0x00005610c5d9d631 in mirror_run (job=0x5610c76a2c00, errp=<optimized out>) at ../block/mirror.c:491
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  #2  0x00005610c5d58726 in job_co_entry (opaque=0x5610c76a2c00) at ../job.c:917
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  #3  0x00005610c5f046c6 in coroutine_trampoline (i0=<optimized out>, i1=<optimized out>)
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      at ../util/coroutine-ucontext.c:173
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  #4  0x00007f0909975820 in ?? () at ../sysdeps/unix/sysv/linux/x86_64/__start_context.S:91
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      from /usr/lib64/libc.so.6
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Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2001404
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Fixes: d44dae1a7c ("block/mirror: fix active mirror dead-lock in mirror_wait_on_conflicts")
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Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
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Message-Id: <20210910124533.288318-1-sgarzare@redhat.com>
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Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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Signed-off-by: Hanna Reitz <hreitz@redhat.com>
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(cherry picked from commit 66fed30c9cd11854fc878a4eceb507e915d7c9cd)
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
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---
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 block/mirror.c | 25 ++++++++++++++++---------
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 1 file changed, 16 insertions(+), 9 deletions(-)
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diff --git a/block/mirror.c b/block/mirror.c
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index 98fc66eabf..85b781bc21 100644
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--- a/block/mirror.c
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+++ b/block/mirror.c
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@@ -160,18 +160,25 @@ static void coroutine_fn mirror_wait_on_conflicts(MirrorOp *self,
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             if (ranges_overlap(self_start_chunk, self_nb_chunks,
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                                op_start_chunk, op_nb_chunks))
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             {
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-                /*
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-                 * If the operation is already (indirectly) waiting for us, or
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-                 * will wait for us as soon as it wakes up, then just go on
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-                 * (instead of producing a deadlock in the former case).
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-                 */
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-                if (op->waiting_for_op) {
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-                    continue;
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+                if (self) {
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+                    /*
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+                     * If the operation is already (indirectly) waiting for us,
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+                     * or will wait for us as soon as it wakes up, then just go
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+                     * on (instead of producing a deadlock in the former case).
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+                     */
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+                    if (op->waiting_for_op) {
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+                        continue;
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+                    }
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+
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+                    self->waiting_for_op = op;
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                 }
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-                self->waiting_for_op = op;
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                 qemu_co_queue_wait(&op->waiting_requests, NULL);
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-                self->waiting_for_op = NULL;
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+
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+                if (self) {
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+                    self->waiting_for_op = NULL;
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+                }
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+
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                 break;
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             }
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         }
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