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[OSS-Fuzz] Issue 31875 megasas: Null-ptr dereference in megasas_finish_dcmd
Hello,
== QTest Reproducer ==
/*
* cat << EOF | ./qemu-system-i386 -display none -machine accel=qtest, -m \
* 512M -machine q35 -nodefaults -device megasas -device \
* scsi-cd,drive=null0 -blockdev \
* driver=null-co,read-zeroes=on,node-name=null0 -qtest stdio
* outl 0xcf8 0x80000801
* outl 0xcfc 0x05000000
* outl 0xcf8 0x80000816
* outl 0xcfc 0x19000000
* write 0x1e1ed300 0x1 0x01
* write 0x1e1ed307 0x1 0x01
* write 0x1e1ed316 0x1 0x01
* write 0x1e1ed328 0x1 0x01
* write 0x1e1ed32f 0x1 0x01
* outl 0x1940 0x1e1ed300
* outl 0x19c0 0x00
* EOF
*/
static void null_deref_megasas_finish_dcmd(void)
{
QTestState *s = qtest_init(
"-display none , -m 512M -machine q35 -nodefaults -device megasas -device "
"scsi-cd,drive=null0 -blockdev driver=null-co,read-zeroes=on,node-name=null0 ");
qtest_outl(s, 0xcf8, 0x80000801);
qtest_outl(s, 0xcfc, 0x05000000);
qtest_outl(s, 0xcf8, 0x80000816);
qtest_outl(s, 0xcfc, 0x19000000);
qtest_bufwrite(s, 0x1e1ed300, "\x01", 0x1);
qtest_bufwrite(s, 0x1e1ed307, "\x01", 0x1);
qtest_bufwrite(s, 0x1e1ed316, "\x01", 0x1);
qtest_bufwrite(s, 0x1e1ed328, "\x01", 0x1);
qtest_bufwrite(s, 0x1e1ed32f, "\x01", 0x1);
qtest_outl(s, 0x1940, 0x1e1ed300);
qtest_outl(s, 0x19c0, 0x00);
qtest_quit(s);
}
int main(int argc, char **argv)
{
const char *arch = qtest_get_arch();
g_test_init(&argc, &argv, NULL);
if (strcmp(arch, "i386") == 0) {
qtest_add_func("fuzz/null_deref_megasas_finish_dcmd",
null_deref_megasas_finish_dcmd);
}
return g_test_run();
}
== Stack Trace ==
../hw/scsi/megasas.c:1884:21: runtime error: member access within null pointer of type 'union mfi_frame'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior ../hw/scsi/megasas.c:1884:21 in
../hw/scsi/megasas.c:1884:21: runtime error: member access within null pointer of type 'struct mfi_frame_header'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior ../hw/scsi/megasas.c:1884:21 in
AddressSanitizer:DEADLYSIGNAL
=================================================================
==314546==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000003 (pc 0x55b1b4f4de73 bp 0x7ffcfc5a8bb0 sp 0x7ffcfc5a8900 T0)
==314546==The signal is caused by a WRITE memory access.
==314546==Hint: address points to the zero page.
#0 0x55b1b4f4de73 in megasas_command_complete build/../hw/scsi/megasas.c:1884:40
#1 0x55b1b5613914 in scsi_req_complete build/../hw/scsi/scsi-bus.c:1515:5
#2 0x55b1b5448aeb in scsi_dma_complete_noio build/../hw/scsi/scsi-disk.c:345:9
#3 0x55b1b5446fc7 in scsi_dma_complete build/../hw/scsi/scsi-disk.c:366:5
#4 0x55b1b4fffc56 in dma_complete build/../softmmu/dma-helpers.c:121:9
#5 0x55b1b4fffc56 in dma_blk_cb build/../softmmu/dma-helpers.c:139:9
#6 0x55b1b6856016 in blk_aio_complete build/../block/block-backend.c:1412:9
#7 0x55b1b6f48b06 in aio_bh_poll build/../util/async.c:164:13
#8 0x55b1b6f08cec in aio_dispatch build/../util/aio-posix.c:381:5
#9 0x55b1b6f4d59c in aio_ctx_dispatch build/../util/async.c:306:5
#10 0x7fd88c098baa in g_main_context_dispatch (/usr/lib/x86_64-linux-gnu/libglib-2.0.so.0+0x51baa)
#11 0x55b1b6f59a3c in glib_pollfds_poll build/../util/main-loop.c:232:9
#12 0x55b1b6f59a3c in os_host_main_loop_wait build/../util/main-loop.c:255:5
#13 0x55b1b6f59a3c in main_loop_wait build/../util/main-loop.c:531:11
#14 0x55b1b61a78a9 in qemu_main_loop build/../softmmu/runstate.c:725:9
#15 0x55b1b4c751e5 in main build/../softmmu/main.c:50:5
#16 0x7fd88aec6d09 in __libc_start_main csu/../csu/libc-start.c:308:16
#17 0x55b1b4bc8bb9 in _start (system-i386+0x2b5fbb9)
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