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hw/sd/sdcard: Fix assertion accessing out-of-range addresses with CMD30

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OSS-Fuzz found sending illegal addresses when querying the write
protection bits triggers the assertion added in commit 84816fb63e
("hw/sd/sdcard: Assert if accessing an illegal group"):

  qemu-fuzz-i386-target-generic-fuzz-sdhci-v3: ../hw/sd/sd.c:824: uint32_t sd_wpbits(SDState *, uint64_t):
  Assertion `wpnum < sd->wpgrps_size' failed.
  #3 0x7f62a8b22c91 in __assert_fail
  #4 0x5569adcec405 in sd_wpbits hw/sd/sd.c:824:9
  #5 0x5569adce5f6d in sd_normal_command hw/sd/sd.c:1389:38
  #6 0x5569adce3870 in sd_do_command hw/sd/sd.c:1737:17
  #7 0x5569adcf1566 in sdbus_do_command hw/sd/core.c💯16
  #8 0x5569adcfc192 in sdhci_send_command hw/sd/sdhci.c:337:12
  #9 0x5569adcfa3a3 in sdhci_write hw/sd/sdhci.c:1186:9
  #10 0x5569adfb3447 in memory_region_write_accessor softmmu/memory.c:492:5

It is legal for the CMD30 to query for out-of-range addresses.
Such invalid addresses are simply ignored in the response (write
protection bits set to 0).

In commit 84816fb63e ("hw/sd/sdcard: Assert if accessing an illegal
group") we misplaced the assertion *before* we test the address is
in range. Move it *after*.

Include the qtest reproducer provided by Alexander Bulekov:

  $ make check-qtest-i386
  ...
  Running test qtest-i386/fuzz-sdcard-test
  qemu-system-i386: ../hw/sd/sd.c:824: sd_wpbits: Assertion `wpnum < sd->wpgrps_size' failed.

Cc: qemu-stable@nongnu.org
Reported-by: OSS-Fuzz (Issue 29225)
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Fixes: 84816fb63e ("hw/sd/sdcard: Assert if accessing an illegal group")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/495
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210802235524.3417739-3-f4bug@amsat.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Alexander Bulekov <alxndr@bu.edu>
This commit is contained in:
Philippe Mathieu-Daudé 2021-08-03 01:55:24 +02:00
parent 2a0396285d
commit 4ac0b72bae
2 changed files with 37 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
hw/sd/sd.c
View File

@ -821,7 +821,6 @@ static uint32_t sd_wpbits(SDState *sd, uint64_t addr)
wpnum = sd_addr_to_wpnum(addr);
for (i = 0; i < 32; i++, wpnum++, addr += WPGROUP_SIZE) {
assert(wpnum < sd->wpgrps_size);
if (addr >= sd->size) {
/*
* If the addresses of the last groups are outside the valid range,
@ -829,6 +828,7 @@ static uint32_t sd_wpbits(SDState *sd, uint64_t addr)
*/
continue;
}
assert(wpnum < sd->wpgrps_size);
if (test_bit(wpnum, sd->wp_groups)) {
ret |= (1 << i);
}

36
tests/qtest/fuzz-sdcard-test.c
View File

@ -52,6 +52,41 @@ static void oss_fuzz_29225(void)
qtest_quit(s);
}
/*
* https://gitlab.com/qemu-project/qemu/-/issues/495
* Used to trigger:
* Assertion `wpnum < sd->wpgrps_size' failed.
*/
static void oss_fuzz_36217(void)
{
QTestState *s;
s = qtest_init(" -display none -m 32 -nodefaults -nographic"
" -device sdhci-pci,sd-spec-version=3 "
"-device sd-card,drive=d0 "
"-drive if=none,index=0,file=null-co://,format=raw,id=d0");
qtest_outl(s, 0xcf8, 0x80001010);
qtest_outl(s, 0xcfc, 0xe0000000);
qtest_outl(s, 0xcf8, 0x80001004);
qtest_outw(s, 0xcfc, 0x02);
qtest_bufwrite(s, 0xe000002c, "\x05", 0x1);
qtest_bufwrite(s, 0xe000000f, "\x37", 0x1);
qtest_bufwrite(s, 0xe000000a, "\x01", 0x1);
qtest_bufwrite(s, 0xe000000f, "\x29", 0x1);
qtest_bufwrite(s, 0xe000000f, "\x02", 0x1);
qtest_bufwrite(s, 0xe000000f, "\x03", 0x1);
qtest_bufwrite(s, 0xe0000005, "\x01", 0x1);
qtest_bufwrite(s, 0xe000000f, "\x06", 0x1);
qtest_bufwrite(s, 0xe000000c, "\x05", 0x1);
qtest_bufwrite(s, 0xe000000e, "\x20", 0x1);
qtest_bufwrite(s, 0xe000000f, "\x08", 0x1);
qtest_bufwrite(s, 0xe000000b, "\x3d", 0x1);
qtest_bufwrite(s, 0xe000000f, "\x1e", 0x1);
qtest_quit(s);
}
int main(int argc, char **argv)
{
const char *arch = qtest_get_arch();
@ -60,6 +95,7 @@ int main(int argc, char **argv)
if (strcmp(arch, "i386") == 0) {
qtest_add_func("fuzz/sdcard/oss_fuzz_29225", oss_fuzz_29225);
qtest_add_func("fuzz/sdcard/oss_fuzz_36217", oss_fuzz_36217);
}
return g_test_run();