CVE-2023-53222

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> jfs: jfs_dmap: Validate db_l2nbperpage while mounting<br /> <br /> In jfs_dmap.c at line 381, BLKTODMAP is used to get a logical block<br /> number inside dbFree(). db_l2nbperpage, which is the log2 number of<br /> blocks per page, is passed as an argument to BLKTODMAP which uses it<br /> for shifting.<br /> <br /> Syzbot reported a shift out-of-bounds crash because db_l2nbperpage is<br /> too big. This happens because the large value is set without any<br /> validation in dbMount() at line 181.<br /> <br /> Thus, make sure that db_l2nbperpage is correct while mounting.<br /> <br /> Max number of blocks per page = Page size / Min block size<br /> =&gt; log2(Max num_block per page) = log2(Page size / Min block size)<br /> = log2(Page size) - log2(Min block size)<br /> <br /> =&gt; Max db_l2nbperpage = L2PSIZE - L2MINBLOCKSIZE