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

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>
(cherry picked from commit 4ac0b72bae)
*drop fuzz test additions, since sdcard fuzz test has functional
 dependency on guest-visible change not flagged for stable:
 59b63d78 ("hw/sd/sdcard: Check for valid address range in SEND_WRITE_PROT (CMD30)")
Signed-off-by: Michael Roth <michael.roth@amd.com>
stable-6.0
Philippe Mathieu-Daudé 2021-08-03 01:55:24 +02:00 committed by Michael Roth
parent 21611dd0a5
commit 978c11b013
1 changed files with 1 additions and 1 deletions
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2
hw/sd/sd.c
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@ -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);
}