CVE-2024-26720

Description

In the Linux kernel, the following vulnerability has been resolved: mm/writeback: fix possible divide-by-zero in wb_dirty_limits(), again (struct dirty_throttle_control *)->thresh is an unsigned long, but is passed as the u32 divisor argument to div_u64(). On architectures where unsigned long is 64 bytes, the argument will be implicitly truncated. Use div64_u64() instead of div_u64() so that the value used in the "is this a safe division" check is the same as the divisor. Also, remove redundant cast of the numerator to u64, as that should happen implicitly. This would be difficult to exploit in memcg domain, given the ratio-based arithmetic domain_drity_limits() uses, but is much easier in global writeback domain with a BDI_CAP_STRICTLIMIT-backing device, using e.g. vm.dirty_bytes=(1<<32)*PAGE_SIZE so that dtc->thresh == (1<<32)

Product status

References

https://git.kernel.org/stable/c/c593d26fb5d577ef31b6e49a31e08ae3ebc1bc1e

https://git.kernel.org/stable/c/253f9ea7e8e53a5176bd80ceb174907b10724c1a

https://git.kernel.org/stable/c/1f12e4b3284d6c863f272eb2de0d4248ed211cf4

https://git.kernel.org/stable/c/23a28f5f3f6ca1e4184bd0e9631cd0944cf1c807

https://git.kernel.org/stable/c/81e7d2530d458548b90a5c5e76b77ad5e5d1c0df

https://git.kernel.org/stable/c/145faa3d03688cbb7bbaaecbd84c01539852942c

https://git.kernel.org/stable/c/5099871b370335809c0fd1abad74d9c7c205d43f

https://git.kernel.org/stable/c/2820005edae13b140f2d54267d1bd6bb23915f59

https://git.kernel.org/stable/c/16b1025eaa8fc223ab4273ece20d1c3a4211a95d

https://git.kernel.org/stable/c/cbbe17a324437c0ff99881a3ee453da45b228a00

https://git.kernel.org/stable/c/ec18ec230301583395576915d274b407743d8f6c

https://git.kernel.org/stable/c/f6620df12cb6bdcad671d269debbb23573502f9d

https://git.kernel.org/stable/c/65977bed167a92e87085e757fffa5798f7314c9f

https://git.kernel.org/stable/c/9319b647902cbd5cc884ac08a8a6d54ce111fc78

https://git.kernel.org/stable/c/000099d71648504fb9c7a4616f92c2b70c3e44ec

cve.org CVE-2024-26720

nvd.nist.gov CVE-2024-26720

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