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PUBLISHED

CVE-2024-26720

mm/writeback: fix possible divide-by-zero in wb_dirty_limits(), again

Reserved:2024-02-19
Published:2024-04-03
Updated:2024-04-03

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

Default status
unaffected

f6789593d5ce before c593d26fb5d5
affected

f6789593d5ce before 1f12e4b3284d
affected

f6789593d5ce before 81e7d2530d45
affected

f6789593d5ce before 5099871b3703
affected

f6789593d5ce before 16b1025eaa8f
affected

f6789593d5ce before ec18ec230301
affected

f6789593d5ce before 65977bed167a
affected

f6789593d5ce before 9319b647902c
affected

Default status
affected

3.16
affected

Any version before 3.16
unaffected

4.19.307
unaffected

5.4.269
unaffected

5.10.210
unaffected

5.15.149
unaffected

6.1.79
unaffected

6.6.18
unaffected

6.7.6
unaffected

6.8
unaffected

References

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

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

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

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

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

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

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

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

cve.org CVE-2024-26720

nvd.nist.gov CVE-2024-26720

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