mirror of
https://github.com/qemu/qemu.git
synced 2024-11-26 21:33:40 +08:00
hw/display/xlnx_dp: Avoid crash when reading empty RX FIFO
In the previous commit we fixed a crash when the guest read a register that pop from an empty FIFO. By auditing the repository, we found another similar use with an easy way to reproduce: $ qemu-system-aarch64 -M xlnx-zcu102 -monitor stdio -S QEMU 4.0.50 monitor - type 'help' for more information (qemu) xp/b 0xfd4a0134 Aborted (core dumped) (gdb) bt #0 0x00007f6936dea57f in raise () at /lib64/libc.so.6 #1 0x00007f6936dd4895 in abort () at /lib64/libc.so.6 #2 0x0000561ad32975ec in xlnx_dp_aux_pop_rx_fifo (s=0x7f692babee70) at hw/display/xlnx_dp.c:431 #3 0x0000561ad3297dc0 in xlnx_dp_read (opaque=0x7f692babee70, offset=77, size=4) at hw/display/xlnx_dp.c:667 #4 0x0000561ad321b896 in memory_region_read_accessor (mr=0x7f692babf620, addr=308, value=0x7ffe05c1db88, size=4, shift=0, mask=4294967295, attrs=...) at memory.c:439 #5 0x0000561ad321bd70 in access_with_adjusted_size (addr=308, value=0x7ffe05c1db88, size=1, access_size_min=4, access_size_max=4, access_fn=0x561ad321b858 <memory_region_read_accessor>, mr=0x7f692babf620, attrs=...) at memory.c:569 #6 0x0000561ad321e9d5 in memory_region_dispatch_read1 (mr=0x7f692babf620, addr=308, pval=0x7ffe05c1db88, size=1, attrs=...) at memory.c:1420 #7 0x0000561ad321ea9d in memory_region_dispatch_read (mr=0x7f692babf620, addr=308, pval=0x7ffe05c1db88, size=1, attrs=...) at memory.c:1447 #8 0x0000561ad31bd742 in flatview_read_continue (fv=0x561ad69c04f0, addr=4249485620, attrs=..., buf=0x7ffe05c1dcf0 "\020\335\301\005\376\177", len=1, addr1=308, l=1, mr=0x7f692babf620) at exec.c:3385 #9 0x0000561ad31bd895 in flatview_read (fv=0x561ad69c04f0, addr=4249485620, attrs=..., buf=0x7ffe05c1dcf0 "\020\335\301\005\376\177", len=1) at exec.c:3423 #10 0x0000561ad31bd90b in address_space_read_full (as=0x561ad5bb3020, addr=4249485620, attrs=..., buf=0x7ffe05c1dcf0 "\020\335\301\005\376\177", len=1) at exec.c:3436 #11 0x0000561ad33b1c42 in address_space_read (len=1, buf=0x7ffe05c1dcf0 "\020\335\301\005\376\177", attrs=..., addr=4249485620, as=0x561ad5bb3020) at include/exec/memory.h:2131 #12 0x0000561ad33b1c42 in memory_dump (mon=0x561ad59c4530, count=1, format=120, wsize=1, addr=4249485620, is_physical=1) at monitor/misc.c:723 #13 0x0000561ad33b1fc1 in hmp_physical_memory_dump (mon=0x561ad59c4530, qdict=0x561ad6c6fd00) at monitor/misc.c:795 #14 0x0000561ad37b4a9f in handle_hmp_command (mon=0x561ad59c4530, cmdline=0x561ad59d0f22 "/b 0x00000000fd4a0134") at monitor/hmp.c:1082 Fix by checking the FIFO is not empty before popping from it. The datasheet is not clear about the reset value of this register, we choose to return '0'. Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Alistair Francis <alistair.francis@wdc.com> Message-id: 20190709113715.7761-4-philmd@redhat.com Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
parent
c0bccee9b4
commit
a09ef50404
@ -427,11 +427,18 @@ static uint8_t xlnx_dp_aux_pop_rx_fifo(XlnxDPState *s)
|
||||
uint8_t ret;
|
||||
|
||||
if (fifo8_is_empty(&s->rx_fifo)) {
|
||||
DPRINTF("rx_fifo underflow..\n");
|
||||
abort();
|
||||
qemu_log_mask(LOG_GUEST_ERROR,
|
||||
"%s: Reading empty RX_FIFO\n",
|
||||
__func__);
|
||||
/*
|
||||
* The datasheet is not clear about the reset value, it seems
|
||||
* to be unspecified. We choose to return '0'.
|
||||
*/
|
||||
ret = 0;
|
||||
} else {
|
||||
ret = fifo8_pop(&s->rx_fifo);
|
||||
DPRINTF("pop 0x%" PRIX8 " from rx_fifo.\n", ret);
|
||||
}
|
||||
ret = fifo8_pop(&s->rx_fifo);
|
||||
DPRINTF("pop 0x%" PRIX8 " from rx_fifo.\n", ret);
|
||||
return ret;
|
||||
}
|
||||
|
||||
|
Loading…
Reference in New Issue
Block a user