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linux/drivers/rapidio/devices
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James Kim 5cbef379a9 rapidio: mport_cdev: fix use-after-free in dma_req_free() 
dma_req_free() acquires buf_mutex through req->map, drops the mapping
reference with kref_put(), and then dereferences req->map again to unlock
the mutex.

If kref_put() drops the last reference, mport_release_mapping() frees the
mapping, and the subsequent mutex_unlock() dereferences a freed object. 
This is a use-after-free.

Fix this by caching map and md before kref_put(), clearing req->map while
holding buf_mutex, and using the cached md for mutex unlocking.

The bug is reachable from userspace via the RapidIO mport character device
interface.

Link: https://lore.kernel.org/20260723235220.588424-1-james010kim@gmail.com
Fixes: e8de370188 ("rapidio: add mport char device driver")
Signed-off-by: James Kim <james010kim@gmail.com>
Reviewed-by: Dan Carpenter <error27@gmail.com>
Cc: Alexandre Bounine <alex.bou9@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
History 2026-08-05 11:20:14 -07:00
..
Kconfig treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
Makefile treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
rio_mport_cdev.c rapidio: mport_cdev: fix use-after-free in dma_req_free() 2026-08-05 11:20:14 -07:00
tsi721.c rapidio/tsi721: prevent a bad dereference in tsi721_db_dpc() 2026-05-28 21:24:45 -07:00
tsi721.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
tsi721_dma.c treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00