From: Philippe Mathieu-Daudé <f4...@amsat.org>
Zhang Zi Ming reported a heap overflow in the Drawing Engine of
the SM501 companion chip model, in particular in the COPY_AREA()
macro in sm501_2d_operation().
Add a simple check to avoid the heap overflow.
This fixes:
=================================================================
==20518==ERROR: AddressSanitizer: heap-buffer-overflow on address
0x7f6f4c3fffff at pc 0x55b1e1d358f0 bp 0x7ffce464dfb0 sp 0x7ffce464dfa8
READ of size 1 at 0x7f6f4c3fffff thread T0
#0 0x55b1e1d358ef in sm501_2d_operation hw/display/sm501.c:788:13
#1 0x55b1e1d32c38 in sm501_2d_engine_write hw/display/sm501.c:1466:13
#2 0x55b1e0cd19d8 in memory_region_write_accessor memory.c:483:5
#3 0x55b1e0cd1404 in access_with_adjusted_size memory.c:544:18
#4 0x55b1e0ccfb9d in memory_region_dispatch_write memory.c:1476:16
#5 0x55b1e0ae55a8 in flatview_write_continue exec.c:3125:23
#6 0x55b1e0ad3e87 in flatview_write exec.c:3165:14
#7 0x55b1e0ad3a24 in address_space_write exec.c:3256:18
0x7f6f4c3fffff is located 4194303 bytes to the right of 4194304-byte region
[0x7f6f4bc00000,0x7f6f4c000000)
allocated by thread T0 here:
#0 0x55b1e0a6e715 in __interceptor_posix_memalign
(ppc64-softmmu/qemu-system-ppc64+0x19c0715)
#1 0x55b1e31c1482 in qemu_try_memalign util/oslib-posix.c:189:11
#2 0x55b1e31c168c in qemu_memalign util/oslib-posix.c:205:27
#3 0x55b1e11a00b3 in spapr_reallocate_hpt hw/ppc/spapr.c:1560:23
#4 0x55b1e11a0ce4 in spapr_setup_hpt hw/ppc/spapr.c:1593:5
#5 0x55b1e11c2fba in spapr_machine_reset hw/ppc/spapr.c:1644:9
#6 0x55b1e1368b01 in qemu_system_reset softmmu/vl.c:1391:9
#7 0x55b1e1375af3 in qemu_init softmmu/vl.c:4436:5
#8 0x55b1e2fc8a59 in main softmmu/main.c:48:5
#9 0x7f6f8150bf42 in __libc_start_main (/lib64/libc.so.6+0x23f42)
SUMMARY: AddressSanitizer: heap-buffer-overflow hw/display/sm501.c:788:13 in
sm501_2d_operation
Shadow bytes around the buggy address:
0x0fee69877fa0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0fee69877fb0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0fee69877fc0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0fee69877fd0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0fee69877fe0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0fee69877ff0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa[fa]
0x0fee69878000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fee69878010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fee69878020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fee69878030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fee69878040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Poisoned by user: f7
ASan internal: fe
==20518==ABORTING
Cc: qemu-sta...@nongnu.org
Fixes: 07d8a50cb0e ("sm501: add 2D engine copyrect support")
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1786026
Reported-by: Zhang Zi Ming <1015138...@qq.com>
Acked-by: BALATON Zoltan <bala...@eik.bme.hu>
Signed-off-by: Philippe Mathieu-Daudé <f4...@amsat.org>
Message-Id: <20200413220100.18628-1-f4...@amsat.org>
Signed-off-by: Philippe Mathieu-Daudé <phi...@redhat.com>
---
hw/display/sm501.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/hw/display/sm501.c b/hw/display/sm501.c
index de0ab9d977..902acb3875 100644
--- a/hw/display/sm501.c
+++ b/hw/display/sm501.c
@@ -726,6 +726,12 @@ static void sm501_2d_operation(SM501State *s)
int crt = (s->dc_crt_control & SM501_DC_CRT_CONTROL_SEL) ? 1 : 0;
int fb_len = get_width(s, crt) * get_height(s, crt) * get_bpp(s, crt);
+ if (rtl && (src_x < operation_width || src_y < operation_height)) {
+ qemu_log_mask(LOG_GUEST_ERROR, "sm501: Illegal RTL address (%i, %i)\n",
+ src_x, src_y);
+ return;
+ }
+
if (addressing != 0x0) {
printf("%s: only XY addressing is supported.\n", __func__);
abort();
--
2.21.1
