| Message ID | 20210728181728.2012952-3-f4bug@amsat.org |
|---|---|
| State | New |
| Headers | show |
| Series | hw/sd/sdcard: Fix assertion accessing out-of-range addresses with CMD30 | expand |
Peter, Bin, could you review this (trivial) patch? This is a regression since 6.1 I'd like to get fixed for v6.1.0-rc2. On 7/28/21 8:17 PM, Philippe Mathieu-Daudé wrote: > OSS-Fuzz found sending illegal addresses when querying the write > protection bits triggers the assertion added in commit 84816fb63e5 > ("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:100:16 > #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). > > Note, we had an off-by-one in the wpgrps_size check since commit > a1bb27b1e98. Since we have a total of 'wpgrps_size' bits, the latest > valid group bit is 'wpgrps_size - 1'. > > Since we now check the group bit is in range, remove the assertion. > > 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) > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/495 > Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org> > --- > hw/sd/sd.c | 4 ++-- > tests/qtest/fuzz-sdcard-test.c | 36 ++++++++++++++++++++++++++++++++++ > 2 files changed, 38 insertions(+), 2 deletions(-) > > diff --git a/hw/sd/sd.c b/hw/sd/sd.c > index 707dcc12a14..273af75c1be 100644 > --- a/hw/sd/sd.c > +++ b/hw/sd/sd.c > @@ -820,8 +820,8 @@ 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); > + for (i = 0; i < 32 && wpnum < sd->wpgrps_size - 1; > + i++, wpnum++, addr += WPGROUP_SIZE) { > if (addr >= sd->size) { > /* > * If the addresses of the last groups are outside the valid range, > diff --git a/tests/qtest/fuzz-sdcard-test.c b/tests/qtest/fuzz-sdcard-test.c > index 96602eac7e5..ae14305344a 100644 > --- a/tests/qtest/fuzz-sdcard-test.c > +++ b/tests/qtest/fuzz-sdcard-test.c > @@ -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(); >
On Wed, 28 Jul 2021 at 19:19, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote: > > OSS-Fuzz found sending illegal addresses when querying the write > protection bits triggers the assertion added in commit 84816fb63e5 > ("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:100:16 > #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). > > Note, we had an off-by-one in the wpgrps_size check since commit > a1bb27b1e98. Since we have a total of 'wpgrps_size' bits, the latest > valid group bit is 'wpgrps_size - 1'. The commit message says "wpgrps_size - 1" is valid... > @@ -820,8 +820,8 @@ 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); > + for (i = 0; i < 32 && wpnum < sd->wpgrps_size - 1; ...but the code change makes the loop terminate when wpnum == wpgrps_size - 1, so we don't execute the loop body for wpgrps_size -1. Which is correct ? > + i++, wpnum++, addr += WPGROUP_SIZE) { thanks -- PMM
On 8/2/21 2:03 PM, Peter Maydell wrote: > On Wed, 28 Jul 2021 at 19:19, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote: >> >> OSS-Fuzz found sending illegal addresses when querying the write >> protection bits triggers the assertion added in commit 84816fb63e5 >> ("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:100:16 >> #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). >> >> Note, we had an off-by-one in the wpgrps_size check since commit >> a1bb27b1e98. Since we have a total of 'wpgrps_size' bits, the latest >> valid group bit is 'wpgrps_size - 1'. > > The commit message says "wpgrps_size - 1" is valid... > >> @@ -820,8 +820,8 @@ 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); >> + for (i = 0; i < 32 && wpnum < sd->wpgrps_size - 1; > > ...but the code change makes the loop terminate when > wpnum == wpgrps_size - 1, so we don't execute the loop > body for wpgrps_size -1. > > Which is correct ? The problem is in sd_reset(), this code is hard for me to follow (and I plan to refactor it during next dev cycle): blk_get_geometry(sd->blk, §); size = sect << 9; sect = sd_addr_to_wpnum(size) + 1; sd->wpgrps_size = sect; sd->wp_groups = bitmap_new(sd->wpgrps_size); CID.WP_GRP_SIZE is defined as: The size of a write protected group. The content of this register is a 7-bit binary coded value, defining the number of erase sectors (see SECTOR_SIZE). The actual size is computed by increasing this number by one. A value of zero means one erase sector, 127 means 128 erase sectors. I think there is a confusion, wpgrps_size holds the real number of erase sectors (used by the model, not returned in the CID.WP_GRP_SIZE register). CID.WP_GRP_SIZE should be (wpgrps_size - 1). Currently we iterate 1 sector number outside of the flash area. To avoid that I used 'wpnum < sd->wpgrps_size - 1' instead of 'wpnum <= sd->wpgrps_size - 1'. But with the fix you suggested responding to the cover, we don't hit this case anymore. So I'll take it and clean the rest later. Thanks, Phil. > >> + i++, wpnum++, addr += WPGROUP_SIZE) { > > thanks > -- PMM >
diff --git a/hw/sd/sd.c b/hw/sd/sd.c index 707dcc12a14..273af75c1be 100644 --- a/hw/sd/sd.c +++ b/hw/sd/sd.c @@ -820,8 +820,8 @@ 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); + for (i = 0; i < 32 && wpnum < sd->wpgrps_size - 1; + i++, wpnum++, addr += WPGROUP_SIZE) { if (addr >= sd->size) { /* * If the addresses of the last groups are outside the valid range, diff --git a/tests/qtest/fuzz-sdcard-test.c b/tests/qtest/fuzz-sdcard-test.c index 96602eac7e5..ae14305344a 100644 --- a/tests/qtest/fuzz-sdcard-test.c +++ b/tests/qtest/fuzz-sdcard-test.c @@ -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();
OSS-Fuzz found sending illegal addresses when querying the write protection bits triggers the assertion added in commit 84816fb63e5 ("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:100:16 #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). Note, we had an off-by-one in the wpgrps_size check since commit a1bb27b1e98. Since we have a total of 'wpgrps_size' bits, the latest valid group bit is 'wpgrps_size - 1'. Since we now check the group bit is in range, remove the assertion. 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) Resolves: https://gitlab.com/qemu-project/qemu/-/issues/495 Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org> --- hw/sd/sd.c | 4 ++-- tests/qtest/fuzz-sdcard-test.c | 36 ++++++++++++++++++++++++++++++++++ 2 files changed, 38 insertions(+), 2 deletions(-)