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This patch is based on Max's original patch. When the qla2xxx firmware is unavailable, eventually qla2x00_sp_timeout() is reached, which calls the timeout function and frees the srb_t instance. The timeout function always resolves to qla2x00_async_iocb_timeout(), which invokes another callback function called "done". All of these qla2x00_*_sp_done() callbacks also free the srb_t instance; after returning to qla2x00_sp_timeout(), it is freed again. The fix is to remove the "sp->free(sp)" call from qla2x00_sp_timeout() and add it to those code paths in qla2x00_async_iocb_timeout() which do not already free the object. This is how it looks like with KASAN: BUG: KASAN: use-after-free in qla2x00_sp_timeout+0x228/0x250 Read of size 8 at addr ffff88278147a590 by task swapper/2/0 Allocated by task 1502: save_stack+0x33/0xa0 kasan_kmalloc+0xa0/0xd0 kmem_cache_alloc+0xb8/0x1c0 mempool_alloc+0xd6/0x260 qla24xx_async_gnl+0x3c5/0x1100 Freed by task 0: save_stack+0x33/0xa0 kasan_slab_free+0x72/0xc0 kmem_cache_free+0x75/0x200 qla24xx_async_gnl_sp_done+0x556/0x9e0 qla2x00_async_iocb_timeout+0x1c7/0x420 qla2x00_sp_timeout+0x16d/0x250 call_timer_fn+0x36/0x200 The buggy address belongs to the object at ffff88278147a440 which belongs to the cache qla2xxx_srbs of size 344 The buggy address is located 336 bytes inside of 344-byte region [ffff88278147a440, ffff88278147a598) Reported-by: Max Kellermann <mk@cm4all.com> Signed-off-by: Quinn Tran <quinn.tran@cavium.com> Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com> Cc: Max Kellermann <mk@cm4all.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.