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

Vulnerability Description

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 it's slightly simplified by removing unnecessary code.

References

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