In the Linux kernel, the following vulnerability has been resolved:
ext4: fix mb_cache_entry’s e_refcnt leak in ext4_xattr_block_cache_find()
Syzbot reports a warning as follows:
This is because when finding an entry in ext4_xattr_block_cache_find(), if
ext4_sb_bread() returns -ENOMEM, the ce’s e_refcnt, which has already grown
in the __entry_find(), won’t be put away, and eventually trigger the above
issue in mb_cache_destroy() due to reference count leakage.
So call mb_cache_entry_put() on the -ENOMEM error branch as a quick fix.
git.kernel.org/stable/c/0c0b4a49d3e7f49690a6827a41faeffad5df7e21
git.kernel.org/stable/c/681ff9a09accd8a4379f8bd30b7a1641ee19bb3e
git.kernel.org/stable/c/76dc776153a47372719d664e0fc50d6355791abb
git.kernel.org/stable/c/896a7e7d0d555ad8b2b46af0c2fa7de7467f9483
git.kernel.org/stable/c/9ad75e78747b5a50dc5a52f0f8e92e920a653f16
git.kernel.org/stable/c/a95df6f04f2c37291adf26a74205cde0314d4577
git.kernel.org/stable/c/b37c0edef4e66fb21a2fbc211471195a383e5ab8
git.kernel.org/stable/c/e941b712e758f615d311946bf98216e79145ccd9