Description

In the Linux kernel, the following vulnerability has been resolved: ocfs2: fix kernel BUG in ocfs2_find_victim_chain syzbot reported a kernel BUG in ocfs2_find_victim_chain() because the `cl_next_free_rec` field of the allocation chain list (next free slot in the chain list) is 0, triggring the BUG_ON(!cl->cl_next_free_rec) condition in ocfs2_find_victim_chain() and panicking the kernel. To fix this, an if condition is introduced in ocfs2_claim_suballoc_bits(), just before calling ocfs2_find_victim_chain(), the code block in it being executed when either of the following conditions is true: 1. `cl_next_free_rec` is equal to 0, indicating that there are no free chains in the allocation chain list 2. `cl_next_free_rec` is greater than `cl_count` (the total number of chains in the allocation chain list) Either of them being true is indicative of the fact that there are no chains left for usage. This is addressed using ocfs2_error(), which prints the error log for debugging purposes, rather than panicking the kernel.

References 7

• git.kernel.org https://git.kernel.org/stable/c/039bef30e320827bac8990c9f29d2a68cd8adb5f
• git.kernel.org https://git.kernel.org/stable/c/1f77e5cd563e6387fdf3bb714fcda36cd88ac5e7
• git.kernel.org https://git.kernel.org/stable/c/7acc0390e0dd7474c4451d05465a677d55ad4268
• git.kernel.org https://git.kernel.org/stable/c/96f1b074c98c20f55a3b23d2ab44d9fb0f619869
• git.kernel.org https://git.kernel.org/stable/c/b08a33d5f80efe6979a6e8f905c1a898910c21dd
• git.kernel.org https://git.kernel.org/stable/c/d0fd1f732ea8063cecd07a3879b7d815c7ee71ed
• git.kernel.org https://git.kernel.org/stable/c/e24aedae71652d4119049f1fbef6532ccbe3966d

Remediation