CVE-2026-89830f2fs: fix valid block count leak on data block allocation failure

Official description

In the Linux kernel, the following vulnerability has been resolved: f2fs: fix valid block count leak on data block allocation failure In __allocate_data_block(), when allocating a new data block (dn->data_blkaddr == NULL_ADDR), inc_valid_block_count() is called first to increment total_valid_block_count and i_blocks. If the subsequent f2fs_allocate_data_block() fails, the function returns the error directly without rolling back the already-incremented block counts, causing a permanent leak. Fix this by calling dec_valid_block_count() to undo the increment before returning the error. The condition old_blkaddr == NULL_ADDR precisely identifies the case where inc_valid_block_count() was called.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/2d50b6d47e5671ff6a25834c5906d443356191f0
• https://git.kernel.org/stable/c/dde99df5a9d3b0ca6ac0a86f98799685f7399432
• https://git.kernel.org/stable/c/931e1aa4d44c52ff8e0feb38420a8827c62e886b
• https://git.kernel.org/stable/c/0f9af07ecc1ab486038373db6ae0436c5d674b19