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qga: Fix ubsan warning

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When compiling QEMU with --enable-ubsan there is a undefined behavior
warning when running "make check":

 .../qga/commands-linux.c:452:15: runtime error: applying non-zero offset 5 to null pointer
 #0 0x55ea7b89450c in build_guest_fsinfo_for_pci_dev ..../qga/commands-linux.c:452:15

Fix it by avoiding the additional pointer variable here and use an
"offset" integer variable instead.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Kostiantyn Kostiuk <kkostiuk@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20250730072709.27077-1-thuth@redhat.com
Signed-off-by: Kostiantyn Kostiuk <kkostiuk@redhat.com>
This commit is contained in:
Thomas Huth 2025-07-30 09:27:09 +02:00 • committed by Kostiantyn Kostiuk
parent e771ba98de
commit 83f6dceb8f
1 changed files with 5 additions and 5 deletions
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10
qga/commands-linux.c
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@ -400,10 +400,10 @@ static bool build_guest_fsinfo_for_pci_dev(char const *syspath,
Error **errp)
{
unsigned int pci[4], host, hosts[8], tgt[3];
int i, nhosts = 0, pcilen;
int i, offset, nhosts = 0, pcilen;
GuestPCIAddress *pciaddr = disk->pci_controller;
bool has_ata = false, has_host = false, has_tgt = false;
char *p, *q, *driver = NULL;
char *p, *driver = NULL;
bool ret = false;
p = strstr(syspath, "/devices/pci");
@ -445,13 +445,13 @@ static bool build_guest_fsinfo_for_pci_dev(char const *syspath,
p = strstr(syspath, "/ata");
if (p) {
q = p + 4;
offset = 4;
has_ata = true;
} else {
p = strstr(syspath, "/host");
q = p + 5;
offset = 5;
}
if (p && sscanf(q, "%u", &host) == 1) {
if (p && sscanf(p + offset, "%u", &host) == 1) {
has_host = true;
nhosts = build_hosts(syspath, p, has_ata, hosts,
ARRAY_SIZE(hosts), errp);