CVE intelligence and bounded remediation

CVE-2024-37356 — In the Linux kernel, the following vulnerability has been resolved: tcp: Fix shift-out-of-bounds in dctcp_update_alpha()

In the Linux kernel, the following vulnerability has been resolved: tcp: Fix shift-out-of-bounds in dctcp_update_alpha(). In dctcp_update_alpha(), we use a module parameter dctcp_shift_g as follows: alpha -= min_not_zero(alpha, alpha >> dctcp_shift_g); ... delivered_ce <<= (10 - dctcp_shift_g); It seems syzkaller started fuzzing module parameters and triggered shift-out-of-bounds [0] by setting 100 to dctcp_shift_g: memcpy((void*)0x20000080, "/sys/module/tcp_dctcp/parameters/dctcp_shift_g\000", 47); res = syscall(__NR_openat, /*fd=*/0xffffffffffffff9cul, /*file=*/0x20000080ul, /*flags=*/2ul, /*mode=*/0ul); memcpy((void*)0x20000000, "100\000", 4); syscall(__NR_write, /*fd=*/r[0], /*val=*/0x20000000ul, /*len=*/4ul); Let's limit the max value of dctcp_shift_g by param_set_uint_minmax(). With this patch: # echo 10 > /sys/module/tcp_dctcp/parameters/dctcp_shift_g # cat /sys/module/tcp_dctcp/parameters/dctcp_shift_g 10 # echo 11 > /sys/module/tcp_dctcp/parameters/dctcp_shift_g -bash: echo: write error: Invalid argument [0]: UBSAN: shift-out-of-bounds in net/ipv4/tcp_dctcp.c:143:12 shift exponent 100 is too large for 32-bit type 'u32' (aka 'unsigned int') CPU: 0 PID: 8083 Comm: syz-execu…

Severity

Medium

CVSS

5.5 (3.1)

Published

2024-06-21

CISA KEV

Not currently listed

Ecosystem

linux/kernel

Weaknesses

CWE-190