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

jfs: jfs_dmap: Validate db_l2nbperpage while mounting

In jfs_dmap.c at line 381, BLKTODMAP is used to get a logical block
number inside dbFree(). db_l2nbperpage, which is the log2 number of
blocks per page, is passed as an argument to BLKTODMAP which uses it
for shifting.

Syzbot reported a shift out-of-bounds crash because db_l2nbperpage is
too big. This happens because the large value is set without any
validation in dbMount() at line 181.

Thus, make sure that db_l2nbperpage is correct while mounting.

Max number of blocks per page = Page size / Min block size
=> log2(Max num_block per page) = log2(Page size / Min block size)
= log2(Page size) - log2(Min block size)

=> Max db_l2nbperpage = L2PSIZE - L2MINBLOCKSIZE

References

• https://nvd.nist.gov/vuln/detail/CVE-2023-53222
• https://git.kernel.org/stable/c/11509910c599cbd04585ec35a6d5e1a0053d84c1
• https://git.kernel.org/stable/c/2a03c4e683d33d17b667418eb717b13dda1fac6b
• https://git.kernel.org/stable/c/47b7eaae08e8b2f25bdf37bc14d21be090bcb20f
• https://git.kernel.org/stable/c/8c1efe3f74a7864461b0dff281c5562154b4aa8e
• https://git.kernel.org/stable/c/a4855aeb13e4ad1f23e16753b68212e180f7d848
• https://git.kernel.org/stable/c/c7feb54b113802d2aba98708769d3c33fb017254
• https://git.kernel.org/stable/c/de984faecddb900fa850af4df574a25b32bb93f5
• https://git.kernel.org/stable/c/ef5c205b6e6f8d1f18ef0b4a9832b1b5fa85f7f2