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usb: gadget: f_ncm: Fix atomic context locking issue

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The ncm_set_alt function was holding a mutex to protect against races
with configfs, which invokes the might-sleep function inside an atomic
context.

Remove the struct net_device pointer from the f_ncm_opts structure to
eliminate the contention. The connection state is now managed by a new
boolean flag to preserve the use-after-free fix from
commit 6334b8e455 ("usb: gadget: f_ncm: Fix UAF ncm object at re-bind
after usb ep transport error").

BUG: sleeping function called from invalid context
Call Trace:
 dump_stack_lvl+0x83/0xc0
 dump_stack+0x14/0x16
 __might_resched+0x389/0x4c0
 __might_sleep+0x8e/0x100
 ...
 __mutex_lock+0x6f/0x1740
 ...
 ncm_set_alt+0x209/0xa40
 set_config+0x6b6/0xb40
 composite_setup+0x734/0x2b40
 ...

Fixes: 56a512a9b4 ("usb: gadget: f_ncm: align net_device lifecycle with bind/unbind")
Cc: stable@kernel.org
Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
Link: https://patch.msgid.link/20260221-legacy-ncm-v2-2-dfb891d76507@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Kuen-Han Tsai 2026-02-21 22:48:16 +08:00 • committed by Greg Kroah-Hartman
commit 0d6c8144ca
3 changed files with 13 additions and 28 deletions
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