CVE-2026-53319
🔶 mediumSummary
In the Linux kernel, the following vulnerability has been resolved: blk-wbt: remove WARN_ON_ONCE from wbt_init_enable_default() wbt_init_enable_default() uses WARN_ON_ONCE to check for failures from wbt_alloc() and wbt_init(). However, both are expected failure paths: - wbt_alloc() can return NULL under memory pressure (-ENOMEM) - wbt_init() can fail with -EBUSY if wbt is already registered syzbot triggers this by injecting memory allocation failures during MTD partition creation via ioctl(B
Description
In the Linux kernel, the following vulnerability has been resolved:
blk-wbt: remove WARN_ON_ONCE from wbt_init_enable_default()
wbt_init_enable_default() uses WARN_ON_ONCE to check for failures from
wbt_alloc() and wbt_init(). However, both are expected failure paths:
- wbt_alloc() can return NULL under memory pressure (-ENOMEM)
- wbt_init() can fail with -EBUSY if wbt is already registered
syzbot triggers this by injecting memory allocation failures during MTD
partition creation via ioctl(BLKPG), causing a spurious warning.
wbt_init_enable_default() is a best-effort initialization called from
blk_register_queue() with a void return type. Failure simply means the
disk operates without writeback throttling, which is harmless.
Replace WARN_ON_ONCE with plain if-checks, consistent with how
wbt_set_lat() in the same file already handles these failures. Add a
pr_warn() for the wbt_init() failure to retain diagnostic information
without triggering a full stack trace.