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authorStefan Hajnoczi <stefanha@redhat.com>2023-04-13 13:19:46 -0400
committerJason Wang <jasowang@redhat.com>2023-05-23 15:20:15 +0800
commit792676c165159c11412346870fd58fd243ab2166 (patch)
tree21157ed0a122ca1bc9c64668b8fe0f020b4292f2 /hw/net
parentc37d98f3a940c832dafd3b77d3f9619df64c8ac4 (diff)
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rtl8139: fix large_send_mss divide-by-zero
If the driver sets large_send_mss to 0 then a divide-by-zero occurs. Even if the division wasn't a problem, the for loop that emits MSS-sized packets would never terminate. Solve these issues by skipping offloading when large_send_mss=0. This issue was found by OSS-Fuzz as part of Alexander Bulekov's device fuzzing work. The reproducer is: $ cat << EOF | ./qemu-system-i386 -display none -machine accel=qtest, -m \ 512M,slots=1,maxmem=0xffff000000000000 -machine q35 -nodefaults -device \ rtl8139,netdev=net0 -netdev user,id=net0 -device \ pc-dimm,id=nv1,memdev=mem1,addr=0xb800a64602800000 -object \ memory-backend-ram,id=mem1,size=2M -qtest stdio outl 0xcf8 0x80000814 outl 0xcfc 0xe0000000 outl 0xcf8 0x80000804 outw 0xcfc 0x06 write 0xe0000037 0x1 0x04 write 0xe00000e0 0x2 0x01 write 0x1 0x1 0x04 write 0x3 0x1 0x98 write 0xa 0x1 0x8c write 0xb 0x1 0x02 write 0xc 0x1 0x46 write 0xd 0x1 0xa6 write 0xf 0x1 0xb8 write 0xb800a646028c000c 0x1 0x08 write 0xb800a646028c000e 0x1 0x47 write 0xb800a646028c0010 0x1 0x02 write 0xb800a646028c0017 0x1 0x06 write 0xb800a646028c0036 0x1 0x80 write 0xe00000d9 0x1 0x40 EOF Buglink: https://gitlab.com/qemu-project/qemu/-/issues/1582 Closes: https://gitlab.com/qemu-project/qemu/-/issues/1582 Cc: qemu-stable@nongnu.org Cc: Peter Maydell <peter.maydell@linaro.org> Fixes: 6d71357a3b65 ("rtl8139: honor large send MSS value") Reported-by: Alexander Bulekov <alxndr@bu.edu> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Tested-by: Alexander Bulekov <alxndr@bu.edu> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
Diffstat (limited to 'hw/net')
-rw-r--r--hw/net/rtl8139.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/hw/net/rtl8139.c b/hw/net/rtl8139.c
index 5a5aaf8..5f1a4d3 100644
--- a/hw/net/rtl8139.c
+++ b/hw/net/rtl8139.c
@@ -2154,6 +2154,9 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s)
int large_send_mss = (txdw0 >> CP_TC_LGSEN_MSS_SHIFT) &
CP_TC_LGSEN_MSS_MASK;
+ if (large_send_mss == 0) {
+ goto skip_offload;
+ }
DPRINTF("+++ C+ mode offloaded task TSO IP data %d "
"frame data %d specified MSS=%d\n",