Description
In the Linux kernel, the following vulnerability has been resolved: ubifs: fix out-of-bounds read in signature length check ubifs_sb_verify_signature() bounds the on-disk ubifs_sig_node->len field before handing the signature payload to verify_pkcs7_signature(), but the check has the wrong sign: if (le32_to_cpu(signode->len) > snod->len + sizeof(struct ubifs_sig_node)) The signature bytes start sizeof(struct ubifs_sig_node) (UBIFS_SIG_NODE_SZ, 64 bytes) into the node, so the payload is at most snod->len - sizeof(struct ubifs_sig_node) bytes long. Adding the header size instead of subtracting it accepts a declared length up to 2 * UBIFS_SIG_NODE_SZ larger than the node actually holds -- past the end of c->sbuf, which is vmalloc(c->leb_size). verify_pkcs7_signature() -> pkcs7_parse_message() -> asn1_ber_decoder() is then handed that inflated length and reads beyond the allocation while walking the DER headers. The node length comes straight from the mounted image, so a crafted signed UBIFS image reaches this via ubifs_read_superblock() before the signature is cryptographically checked. snod->len is guaranteed to be >= UBIFS_SIG_NODE_SZ by the node scanner (c->ranges[UBIFS_SIG_NODE].min_len == UBIFS_SIG_NODE_SZ), so the corrected subtraction cannot underflow. Legitimately signed images are unaffected: a correct superblock never declares a signature longer than the node it is embedded in.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
817aa094842dfc3a6b98c9582d4a647827f66201 to < ab7405bd86331cc2dbc8201699d4adc33bea75e7affected817aa094842dfc3a6b98c9582d4a647827f66201 to < 11abc34698cb3172badf8aa12e623f1bac98bbd8affected817aa094842dfc3a6b98c9582d4a647827f66201 to < 8cc3da72cf57acb4b77442ea8cec48425dff7c06affected817aa094842dfc3a6b98c9582d4a647827f66201 to < 37a9d25a563f5f9103282954ce573c4a61321e7caffected817aa094842dfc3a6b98c9582d4a647827f66201 to < f76b79d6e42af20682495bccd22f72c7164b0018affected817aa094842dfc3a6b98c9582d4a647827f66201 to < a1dc246f98bb94233effa4fa3ec7bf84700bb7d1affected817aa094842dfc3a6b98c9582d4a647827f66201 to < 83e1aa9f5f906c9b1f4949d0521f0f950a159d96affected817aa094842dfc3a6b98c9582d4a647827f66201 to < 95d27c1708bb6e8823c8e7c623f9abc2a91bf4bfaffected
Linux Linux
Default version status: affected
5.3affected0 to < 5.3unaffected5.10.270 to ≤ 5.10.*unaffected5.15.221 to ≤ 5.15.*unaffected6.1.188 to ≤ 6.1.*unaffected6.6.157 to ≤ 6.6.*unaffected6.12.109 to ≤ 6.12.*unaffected6.18.50 to ≤ 6.18.*unaffected7.2.4 to ≤ 7.2.*unaffected7.3 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/ab7405bd86331cc2dbc8201699d4adc33bea75e7 ↗
- https://git.kernel.org/stable/c/11abc34698cb3172badf8aa12e623f1bac98bbd8 ↗
- https://git.kernel.org/stable/c/8cc3da72cf57acb4b77442ea8cec48425dff7c06 ↗
- https://git.kernel.org/stable/c/37a9d25a563f5f9103282954ce573c4a61321e7c ↗
- https://git.kernel.org/stable/c/f76b79d6e42af20682495bccd22f72c7164b0018 ↗
- https://git.kernel.org/stable/c/a1dc246f98bb94233effa4fa3ec7bf84700bb7d1 ↗
- https://git.kernel.org/stable/c/83e1aa9f5f906c9b1f4949d0521f0f950a159d96 ↗
- https://git.kernel.org/stable/c/95d27c1708bb6e8823c8e7c623f9abc2a91bf4bf ↗