Description
In the Linux kernel, the following vulnerability has been resolved: lib/crypto: mpi: Fix integer underflow in mpi_read_raw_from_sgl() Yiming reports an integer underflow in mpi_read_raw_from_sgl() when subtracting "lzeros" from the unsigned "nbytes". For this to happen, the scatterlist "sgl" needs to occupy more bytes than the "nbytes" parameter and the first "nbytes + 1" bytes of the scatterlist must be zero. Under these conditions, the while loop iterating over the scatterlist will count more zeroes than "nbytes", subtract the number of zeroes from "nbytes" and cause the underflow. When commit 2d4d1eea540b ("lib/mpi: Add mpi sgl helpers") originally introduced the bug, it couldn't be triggered because all callers of mpi_read_raw_from_sgl() passed a scatterlist whose length was equal to "nbytes". However since commit 63ba4d67594a ("KEYS: asymmetric: Use new crypto interface without scatterlists"), the underflow can now actually be triggered. When invoking a KEYCTL_PKEY_ENCRYPT system call with a larger "out_len" than "in_len" and filling the "in" buffer with zeroes, crypto_akcipher_sync_prep() will create an all-zero scatterlist used for both the "src" and "dst" member of struct akcipher_request and thereby fulfil the conditions to trigger the bug: sys_keyctl() keyctl_pkey_e_d_s() asymmetric_key_eds_op() software_key_eds_op() crypto_akcipher_sync_encrypt() crypto_akcipher_sync_prep() crypto_akcipher_encrypt() rsa_enc() mpi_read_raw_from_sgl() To the user this will be visible as a DoS as the kernel spins forever, causing soft lockup splats as a side effect. Fix it.
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
2d4d1eea540b27c72488fd1914674c42473d53df to < a1793a48881ec8d26e9c79b0ee65753f1c6846a4affected2d4d1eea540b27c72488fd1914674c42473d53df to < 1abd50fc3cfa16fc2074a3c8c2729c50fd9d7043affected2d4d1eea540b27c72488fd1914674c42473d53df to < 6d63615c796c085b4984e3031b9fa77fffb47360affected2d4d1eea540b27c72488fd1914674c42473d53df to < 2aa77a18dc7f2670497fe3ee5acbeda0b57659e5affected2d4d1eea540b27c72488fd1914674c42473d53df to < 26d3a97ad46c7a9226ec04d4bf35bd4998a97d16affected2d4d1eea540b27c72488fd1914674c42473d53df to < 8637dfb4c1d8a7026ef681f2477c6de8b71c4003affected2d4d1eea540b27c72488fd1914674c42473d53df to < 30e513e755bb381afce6fb57cdc8694136193f22affected2d4d1eea540b27c72488fd1914674c42473d53df to < 8c2f1288250a90a4b5cabed5d888d7e3aeed4035affected
Linux Linux
Default version status: affected
4.4affected0 to < 4.4unaffected5.10.259 to ≤ 5.10.*unaffected5.15.210 to ≤ 5.15.*unaffected6.1.176 to ≤ 6.1.*unaffected6.6.140 to ≤ 6.6.*unaffected6.12.88 to ≤ 6.12.*unaffected6.18.30 to ≤ 6.18.*unaffected7.0.7 to ≤ 7.0.*unaffected7.1 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/a1793a48881ec8d26e9c79b0ee65753f1c6846a4 ↗
- https://git.kernel.org/stable/c/1abd50fc3cfa16fc2074a3c8c2729c50fd9d7043 ↗
- https://git.kernel.org/stable/c/6d63615c796c085b4984e3031b9fa77fffb47360 ↗
- https://git.kernel.org/stable/c/2aa77a18dc7f2670497fe3ee5acbeda0b57659e5 ↗
- https://git.kernel.org/stable/c/26d3a97ad46c7a9226ec04d4bf35bd4998a97d16 ↗
- https://git.kernel.org/stable/c/8637dfb4c1d8a7026ef681f2477c6de8b71c4003 ↗
- https://git.kernel.org/stable/c/30e513e755bb381afce6fb57cdc8694136193f22 ↗
- https://git.kernel.org/stable/c/8c2f1288250a90a4b5cabed5d888d7e3aeed4035 ↗
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html ↗
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html ↗
- https://cert-portal.siemens.com/productcert/html/ssa-784472.html ↗