CVE-2022-49914

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

btrfs: fix inode list leak during backref walking at resolve_indirect_refs()

During backref walking, at resolve_indirect_refs(), if we get an error we jump to the out label and call ulist_free() on the parents ulist, which frees all the elements in the ulist - however that does not free any inode lists that may be attached to elements, through the aux field of a ulist node, so we end up leaking lists if we have any attached to the unodes.

Fix this by calling free_leaf_list() instead of ulist_free() when we exit from resolve_indirect_refs(). The static function free_leaf_list() is moved up for this to be possible and its slightly simplified by removing unnecessary code.

Weakness

The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.

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/2c0329406bb28109c07c6e23e5e3e0fa618a95d7
• https://git.kernel.org/stable/c/396515db923ad5cbeb179d6b88927870b4cbebb7
• https://git.kernel.org/stable/c/5614dc3a47e3310fbc77ea3b67eaadd1c6417bf1
• https://git.kernel.org/stable/c/6ba3479f9e96b9ad460c7e77abc26dd16e5dec4f
• https://git.kernel.org/stable/c/a52e24c7fcc3c5ce3588a14e3663c00868d36623
• https://git.kernel.org/stable/c/b1dc9019bb5f89abae85645de1a2dd4830c1f8e9
• https://git.kernel.org/stable/c/cded2c89774b99b67c98147ae103ea878c92a206