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From d39f6ba78035adbe3772603a1939af1e67464448 Mon Sep 17 00:00:00 2001
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Message-Id: <d39f6ba78035adbe3772603a1939af1e67464448@dist-git>
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From: Luyao Huang <lhuang@redhat.com>
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Date: Wed, 11 Jul 2018 17:29:48 +0200
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Subject: [PATCH] virDomainConfNWFilterInstantiate: initialize @xml to avoid
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 random crash
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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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https://bugzilla.redhat.com/show_bug.cgi?id=1599545
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If the code jump to the cleanup before assigning value to @xml
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libvirtd may crash when it tries to free an uninitialized pointer.
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backtrace:
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0  0x00007ffff428d59c in free () from /lib64/libc.so.6
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1  0x00007ffff721314a in virFree (ptrptr=ptrptr@entry=0x7fffc67f1b00) at util/viralloc.c:582
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2  0x00007ffff7345ac4 in virDomainConfNWFilterInstantiate (vmname=<optimized out>,
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   vmuuid=vmuuid@entry=0x7fffc0181ca8 "߉\237\\۔H\262\206z\340\302f\265\233z", net=<optimized out>,
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   ignoreExists=ignoreExists@entry=true) at conf/domain_nwfilter.c:122
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3  0x00007fffca5a77f6 in qemuProcessFiltersInstantiate (ignoreExists=true, def=0x7fffc0181ca0) at qemu/qemu_process.c:3028
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4  qemuProcessReconnect (opaque=<optimized out>) at qemu/qemu_process.c:7653
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5  0x00007ffff72c4895 in virThreadHelper (data=<optimized out>) at util/virthread.c:206
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6  0x00007ffff45dcdd5 in start_thread () from /lib64/libpthread.so.0
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7  0x00007ffff4305ead in clone () from /lib64/libc.so.6
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Signed-off-by: Luyao Huang <lhuang@redhat.com>
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(cherry picked from commit d7557f5f6f51264c1b5623e97f7b4d5259d4d3b6)
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Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
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Reviewed-by: Ján Tomko <jtomko@redhat.com>
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---
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 src/conf/domain_nwfilter.c | 2 +-
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 1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/src/conf/domain_nwfilter.c b/src/conf/domain_nwfilter.c
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index 948b32481e..24b5f42ddd 100644
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--- a/src/conf/domain_nwfilter.c
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+++ b/src/conf/domain_nwfilter.c
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@@ -90,7 +90,7 @@ virDomainConfNWFilterInstantiate(const char *vmname,
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     virConnectPtr conn = virGetConnectNWFilter();
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     virNWFilterBindingDefPtr def = NULL;
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     virNWFilterBindingPtr binding = NULL;
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-    char *xml;
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+    char *xml = NULL;
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     int ret = -1;
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     VIR_DEBUG("vmname=%s portdev=%s filter=%s ignoreExists=%d",
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-- 
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2.18.0
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