CVE-2023-52983

In the Linux kernel, the following vulnerability has been resolved:

block, bfq: fix uaf for bfqq in bic_set_bfqq()

After commit 64dc8c732f5c (block, bfq: fix possible uaf for bfqq->bic), bic->bfqq will be accessed in bic_set_bfqq(), however, in some context bic->bfqq will be freed, and bic_set_bfqq() is called with the freed bic->bfqq.

Fix the problem by always freeing bfqq after bic_set_bfqq().

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/511c922c5bf6c8a166bea826e702336bc2424140
• https://git.kernel.org/stable/c/7f77f3dab5066a7c9da73d72d1eee895ff84a8d5
• https://git.kernel.org/stable/c/b600de2d7d3a16f9007fad1bdae82a3951a26af2
• https://git.kernel.org/stable/c/cb1876fc33af26d00efdd473311f1b664c77c44e