CVE-2026-53319— blk-wbt: remove WARN_ON_ONCE from wbt_init_enable_default()

blk-wbt: remove WARN_ON_ONCE from wbt_init_enable_default()

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.

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Linux kernel 安全漏洞

Linux kernel是美国Linux基金会开源的操作系统Linux所使用的内核。 Linux kernel 7.0版本存在安全漏洞，该漏洞源于blk-wbt中wbt_init_enable_default()函数使用WARN_ON_ONCE检查wbt_alloc()和wbt_init()的失败情况，可能在内存压力下触发虚假警告，导致内核输出警告信息。

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