From: Juraj Vijtiuk <[email protected]> Fix out of bounds read in blobmsg_parse and blobmsg_check_name. The out of bounds read happens because blob_attr and blobmsg_hdr have flexible array members, whose size is 0 in the corresponding sizeofs. For example the __blob_for_each_attr macro checks whether rem >= sizeof(struct blob_attr). However, what LibFuzzer discovered was, if the input data was only 4 bytes, the data would be casted to blob_attr, and later on blob_data(attr) would be called even though attr->data was empty. The same issue could appear with data larger than 4 bytes, where data wasn't empty, but contained only the start of the blobmsg_hdr struct, and blobmsg_hdr name was empty. The bugs were discovered by fuzzing blobmsg_parse and blobmsg_array_parse with LibFuzzer.
CC: Luka Perkov <[email protected]> Signed-off-by: Juraj Vijtiuk <[email protected]> [fixed from, refactored some checks, added fuzz inputs, updated test results] Signed-off-by: Petr Štetiar <[email protected]> --- blobmsg.c | 40 ++++++++++++++---- tests/cram/test_blob_parse.t | 4 ++ tests/cram/test_blobmsg_parse.t | 32 ++++++++------ ...h-a3585b70f1c7ffbdec10f6dadc964336118485c4 | Bin 0 -> 4 bytes ...h-b3585b70f1c7ffbdec10f6dadc964336118485c4 | Bin 0 -> 6 bytes 5 files changed, 56 insertions(+), 20 deletions(-) create mode 100644 tests/fuzz/corpus/crash-a3585b70f1c7ffbdec10f6dadc964336118485c4 create mode 100644 tests/fuzz/corpus/crash-b3585b70f1c7ffbdec10f6dadc964336118485c4 diff --git a/blobmsg.c b/blobmsg.c index 3e34821cc928..762078436f9b 100644 --- a/blobmsg.c +++ b/blobmsg.c @@ -30,16 +30,38 @@ bool blobmsg_check_attr(const struct blob_attr *attr, bool name) return blobmsg_check_attr_len(attr, name, blob_raw_len(attr)); } +static const struct blobmsg_hdr* blobmsg_hdr_from_blob(const struct blob_attr *attr, size_t len) +{ + if (len < sizeof(struct blob_attr) + sizeof(struct blobmsg_hdr)) + return NULL; + + return blob_data(attr); +} + +static bool blobmsg_hdr_valid_namelen(const struct blobmsg_hdr *hdr, size_t len) +{ + if (len < sizeof(struct blob_attr) + sizeof(struct blobmsg_hdr) + blobmsg_namelen(hdr) + 1) + return false; + + return true; +} + static bool blobmsg_check_name(const struct blob_attr *attr, size_t len, bool name) { char *limit = (char *) attr + len; const struct blobmsg_hdr *hdr; - hdr = blob_data(attr); + hdr = blobmsg_hdr_from_blob(attr, len); + if (!hdr) + return false; + if (name && !hdr->namelen) return false; - if ((char *) hdr->name + blobmsg_namelen(hdr) > limit) + if (name && !blobmsg_hdr_valid_namelen(hdr, len)) + return false; + + if ((char *) hdr->name + blobmsg_namelen(hdr) + 1 > limit) return false; if (blobmsg_namelen(hdr) > (blob_len(attr) - sizeof(struct blobmsg_hdr))) @@ -73,9 +95,6 @@ bool blobmsg_check_attr_len(const struct blob_attr *attr, bool name, size_t len) size_t data_len; int id; - if (len < sizeof(struct blob_attr)) - return false; - if (!blobmsg_check_name(attr, len, name)) return false; @@ -170,11 +189,10 @@ int blobmsg_parse_array(const struct blobmsg_policy *policy, int policy_len, return 0; } - int blobmsg_parse(const struct blobmsg_policy *policy, int policy_len, struct blob_attr **tb, void *data, unsigned int len) { - struct blobmsg_hdr *hdr; + const struct blobmsg_hdr *hdr; struct blob_attr *attr; uint8_t *pslen; int i; @@ -191,7 +209,13 @@ int blobmsg_parse(const struct blobmsg_policy *policy, int policy_len, } __blob_for_each_attr(attr, data, len) { - hdr = blob_data(attr); + hdr = blobmsg_hdr_from_blob(attr, len); + if (!hdr) + return -1; + + if (!blobmsg_hdr_valid_namelen(hdr, len)) + return -1; + for (i = 0; i < policy_len; i++) { if (!policy[i].name) continue; diff --git a/tests/cram/test_blob_parse.t b/tests/cram/test_blob_parse.t index 1fd60bc71122..b6cbbaa811b7 100644 --- a/tests/cram/test_blob_parse.t +++ b/tests/cram/test_blob_parse.t @@ -68,6 +68,10 @@ check that blob_parse is producing expected results: cannot parse cert crash-813f3e68661da09c26d4a87dbb9d5099e92be50f cannot parse cert crash-98595faa58ba01d85ba4fd0b109cd3d490b45795 cannot parse cert crash-98595faa58ba01d85ba4fd0b109cd3d490b45795 + cannot parse cert crash-a3585b70f1c7ffbdec10f6dadc964336118485c4 + cannot parse cert crash-a3585b70f1c7ffbdec10f6dadc964336118485c4 + cannot parse cert crash-b3585b70f1c7ffbdec10f6dadc964336118485c4 + cannot parse cert crash-b3585b70f1c7ffbdec10f6dadc964336118485c4 cannot parse cert crash-d0f3aa7d60a094b021f635d4edb7807c055a4ea1 cannot parse cert crash-d0f3aa7d60a094b021f635d4edb7807c055a4ea1 cannot parse cert crash-df9d1243057b27bbad6211e5a23d1cb699028aa2 diff --git a/tests/cram/test_blobmsg_parse.t b/tests/cram/test_blobmsg_parse.t index 37e09ce33f1a..afed22c0e603 100644 --- a/tests/cram/test_blobmsg_parse.t +++ b/tests/cram/test_blobmsg_parse.t @@ -27,37 +27,45 @@ check that blobmsg_parse is producing expected results: crash-333757b203a44751d3535f24b05f467183a96d09: blobmsg_parse_array: ... (0) crash-333757b203a44751d3535f24b05f467183a96d09: blobmsg_parse: ... (0) crash-333757b203a44751d3535f24b05f467183a96d09: blobmsg_parse_array: ... (0) - crash-4c4d2c3c9ade5da9347534e290305c3b9760f627: blobmsg_parse: ... (0) + crash-4c4d2c3c9ade5da9347534e290305c3b9760f627: blobmsg_parse: ... (-1) crash-4c4d2c3c9ade5da9347534e290305c3b9760f627: blobmsg_parse_array: ... (-1) - crash-4c4d2c3c9ade5da9347534e290305c3b9760f627: blobmsg_parse: ... (0) + crash-4c4d2c3c9ade5da9347534e290305c3b9760f627: blobmsg_parse: ... (-1) crash-4c4d2c3c9ade5da9347534e290305c3b9760f627: blobmsg_parse_array: ... (-1) - crash-5e9937b197c88bf4e7b7ee2612456cad4cb83f5b: blobmsg_parse: ... (0) + crash-5e9937b197c88bf4e7b7ee2612456cad4cb83f5b: blobmsg_parse: ... (-1) crash-5e9937b197c88bf4e7b7ee2612456cad4cb83f5b: blobmsg_parse_array: ... (-1) - crash-5e9937b197c88bf4e7b7ee2612456cad4cb83f5b: blobmsg_parse: ... (0) + crash-5e9937b197c88bf4e7b7ee2612456cad4cb83f5b: blobmsg_parse: ... (-1) crash-5e9937b197c88bf4e7b7ee2612456cad4cb83f5b: blobmsg_parse_array: ... (-1) - crash-75b146c4e6fac64d3e62236b27c64b50657bab2a: blobmsg_parse: ... (0) + crash-75b146c4e6fac64d3e62236b27c64b50657bab2a: blobmsg_parse: ... (-1) crash-75b146c4e6fac64d3e62236b27c64b50657bab2a: blobmsg_parse_array: ... (-1) - crash-75b146c4e6fac64d3e62236b27c64b50657bab2a: blobmsg_parse: ... (0) + crash-75b146c4e6fac64d3e62236b27c64b50657bab2a: blobmsg_parse: ... (-1) crash-75b146c4e6fac64d3e62236b27c64b50657bab2a: blobmsg_parse_array: ... (-1) - crash-813f3e68661da09c26d4a87dbb9d5099e92be50f: blobmsg_parse: ... (0) + crash-813f3e68661da09c26d4a87dbb9d5099e92be50f: blobmsg_parse: ... (-1) crash-813f3e68661da09c26d4a87dbb9d5099e92be50f: blobmsg_parse_array: ... (-1) - crash-813f3e68661da09c26d4a87dbb9d5099e92be50f: blobmsg_parse: ... (0) + crash-813f3e68661da09c26d4a87dbb9d5099e92be50f: blobmsg_parse: ... (-1) crash-813f3e68661da09c26d4a87dbb9d5099e92be50f: blobmsg_parse_array: ... (-1) crash-98595faa58ba01d85ba4fd0b109cd3d490b45795: blobmsg_parse: ... (0) crash-98595faa58ba01d85ba4fd0b109cd3d490b45795: blobmsg_parse_array: ... (0) crash-98595faa58ba01d85ba4fd0b109cd3d490b45795: blobmsg_parse: ... (0) crash-98595faa58ba01d85ba4fd0b109cd3d490b45795: blobmsg_parse_array: ... (0) + crash-a3585b70f1c7ffbdec10f6dadc964336118485c4: blobmsg_parse: ... (-1) + crash-a3585b70f1c7ffbdec10f6dadc964336118485c4: blobmsg_parse_array: ... (-1) + crash-a3585b70f1c7ffbdec10f6dadc964336118485c4: blobmsg_parse: ... (-1) + crash-a3585b70f1c7ffbdec10f6dadc964336118485c4: blobmsg_parse_array: ... (-1) + crash-b3585b70f1c7ffbdec10f6dadc964336118485c4: blobmsg_parse: ... (-1) + crash-b3585b70f1c7ffbdec10f6dadc964336118485c4: blobmsg_parse_array: ... (-1) + crash-b3585b70f1c7ffbdec10f6dadc964336118485c4: blobmsg_parse: ... (-1) + crash-b3585b70f1c7ffbdec10f6dadc964336118485c4: blobmsg_parse_array: ... (-1) crash-d0f3aa7d60a094b021f635d4edb7807c055a4ea1: blobmsg_parse: ... (0) crash-d0f3aa7d60a094b021f635d4edb7807c055a4ea1: blobmsg_parse_array: ... (0) crash-d0f3aa7d60a094b021f635d4edb7807c055a4ea1: blobmsg_parse: ... (0) crash-d0f3aa7d60a094b021f635d4edb7807c055a4ea1: blobmsg_parse_array: ... (0) - crash-df9d1243057b27bbad6211e5a23d1cb699028aa2: blobmsg_parse: ... (0) + crash-df9d1243057b27bbad6211e5a23d1cb699028aa2: blobmsg_parse: ... (-1) crash-df9d1243057b27bbad6211e5a23d1cb699028aa2: blobmsg_parse_array: ... (0) - crash-df9d1243057b27bbad6211e5a23d1cb699028aa2: blobmsg_parse: ... (0) + crash-df9d1243057b27bbad6211e5a23d1cb699028aa2: blobmsg_parse: ... (-1) crash-df9d1243057b27bbad6211e5a23d1cb699028aa2: blobmsg_parse_array: ... (0) - crash-e2fd5ecb3b37926743256f1083f47a07c39e10c2: blobmsg_parse: ... (0) + crash-e2fd5ecb3b37926743256f1083f47a07c39e10c2: blobmsg_parse: ... (-1) crash-e2fd5ecb3b37926743256f1083f47a07c39e10c2: blobmsg_parse_array: ... (-1) - crash-e2fd5ecb3b37926743256f1083f47a07c39e10c2: blobmsg_parse: ... (0) + crash-e2fd5ecb3b37926743256f1083f47a07c39e10c2: blobmsg_parse: ... (-1) crash-e2fd5ecb3b37926743256f1083f47a07c39e10c2: blobmsg_parse_array: ... (-1) valid-blobmsg.bin: blobmsg_parse: MLT (0) valid-blobmsg.bin: blobmsg_parse_array: MLT (0) diff --git a/tests/fuzz/corpus/crash-a3585b70f1c7ffbdec10f6dadc964336118485c4 b/tests/fuzz/corpus/crash-a3585b70f1c7ffbdec10f6dadc964336118485c4 new file mode 100644 index 0000000000000000000000000000000000000000..879ba4da035f961e72cd9ae389b4e29c7d298594 GIT binary patch literal 4 LcmZQ(U|<0N02BZS literal 0 HcmV?d00001 diff --git a/tests/fuzz/corpus/crash-b3585b70f1c7ffbdec10f6dadc964336118485c4 b/tests/fuzz/corpus/crash-b3585b70f1c7ffbdec10f6dadc964336118485c4 new file mode 100644 index 0000000000000000000000000000000000000000..12b832b5cd7868045d38706d6dd341e6516e687a GIT binary patch literal 6 NcmZQ(U|?oo0000X00#g7 literal 0 HcmV?d00001 _______________________________________________ openwrt-devel mailing list [email protected] https://lists.openwrt.org/mailman/listinfo/openwrt-devel
