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ebe6674292
rfcomm_kill_listener() walks session_list and deletes every session
without holding rfcomm_mutex, unlike the normal session processing and
connect error paths.
Under normal operation, an open RFCOMM socket pins rfcomm.ko, so
rfcomm_kill_listener() does not run concurrently with rfcomm_dlc_open().
However, forced module unload via delete_module(O_TRUNC) can stop
krfcommd while a failed connect is still unwinding.
connect task forced unload / krfcommd
------------ ------------------------
rfcomm_lock()
rfcomm_session_add()
delete_module("rfcomm", O_TRUNC)
rfcomm_kill_listener()
fetch session from session_list
kernel_connect() fails
rfcomm_session_del()
remove and free session
rfcomm_session_del(session)
The final call then reads the freed session and may corrupt the list.
KASAN reported with mdelay() to enlarge critical window:
BUG: KASAN: slab-use-after-free in rfcomm_run+0x3802/0x3f00 [rfcomm]
Read of size 8 at addr ffff888111058d40 by task krfcommd/79
Tainted: [R]=FORCED_RMMOD
Allocated by task 86:
rfcomm_session_add+0xa1/0x300 [rfcomm]
rfcomm_dlc_open+0x8b2/0xf30 [rfcomm]
rfcomm_sock_connect+0x34c/0x530 [rfcomm]
Freed by task 86:
kfree+0x121/0x3c0
rfcomm_dlc_open+0xab7/0xf30 [rfcomm]
rfcomm_sock_connect+0x34c/0x530 [rfcomm]
Hold rfcomm_mutex across the teardown traversal so every reachable
session_list walk uses the same serialization.
Reviewed-by: Ali Ahmet Memis <ali@iusegentoo.com>
Tested-by: Ali Ahmet Memis <ali@iusegentoo.com>
Reviewed-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Chengfeng Ye <nicoyip.dev@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>