CVE-2022-49927

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

nfs4: Fix kmemleak when allocate slot failed

If one of the slot allocate failed, should cleanup all the other allocated slots, otherwise, the allocated slots will leak:

unreferenced object 0xffff8881115aa100 (size 64): comm mount.nfs, pid 679, jiffies 4294744957 (age 115.037s) hex dump (first 32 bytes): 00 cc 19 73 81 88 ff ff 00 a0 5a 11 81 88 ff ff …s……Z….. 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ……………. backtrace: [<000000007a4c434a>] nfs4_find_or_create_slot+0x8e/0x130 [<000000005472a39c>] nfs4_realloc_slot_table+0x23f/0x270 [<00000000cd8ca0eb>] nfs40_init_client+0x4a/0x90 [<00000000128486db>] nfs4_init_client+0xce/0x270 [<000000008d2cacad>] nfs4_set_client+0x1a2/0x2b0 [<000000000e593b52>] nfs4_create_server+0x300/0x5f0 [<00000000e4425dd2>] nfs4_try_get_tree+0x65/0x110 [<00000000d3a6176f>] vfs_get_tree+0x41/0xf0 [<0000000016b5ad4c>] path_mount+0x9b3/0xdd0 [<00000000494cae71>] __x64_sys_mount+0x190/0x1d0 [<000000005d56bdec>] do_syscall_64+0x35/0x80 [<00000000687c9ae4>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

Weakness

The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory.

Affected Software

Potential Mitigations

• Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
• For example, glibc in Linux provides protection against free of invalid pointers.
• When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
• To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

References

• https://git.kernel.org/stable/c/24641993a7dce6b1628645f4e1d97ca06c9f765d
• https://git.kernel.org/stable/c/45aea4fbf61e205649c29200726b9f45c1718a67
• https://git.kernel.org/stable/c/7e8436728e22181c3f12a5dbabd35ed3a8b8c593
• https://git.kernel.org/stable/c/84b5cb476903003ae9ca88f32b57ff0eaefa6d4c
• https://git.kernel.org/stable/c/86ce0e93cf6fb4d0c447323ac66577c642628b9d
• https://git.kernel.org/stable/c/925cb538bd5851154602818dc80bf4b4d924c127
• https://git.kernel.org/stable/c/aae35a0c8a775fa4afa6a4e7dab3f936f1f89bbb
• https://git.kernel.org/stable/c/db333ae981fb8843c383aa7dbf62cc682597d401