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Commit b27e7519 authored by Duoming Zhou's avatar Duoming Zhou Committed by Greg Kroah-Hartman
Browse files

tty: n_gsm: fix sleep-in-atomic-context bug in gsm_control_send 



[ Upstream commit 7b7dfe4833c70a11cdfa51b38705103bd31eddaa ]

The function gsm_dlci_t1() is a timer handler that runs in an
atomic context, but it calls "kzalloc(..., GFP_KERNEL)" that
may sleep. As a result, the sleep-in-atomic-context bug will
happen. The process is shown below:

gsm_dlci_t1()
 gsm_dlci_open()
  gsm_modem_update()
   gsm_modem_upd_via_msc()
    gsm_control_send()
     kzalloc(sizeof(.., GFP_KERNEL) //may sleep

This patch changes the gfp_t parameter of kzalloc() from GFP_KERNEL to
GFP_ATOMIC in order to mitigate the bug.

Fixes: e1eaea46 ("tty: n_gsm line discipline")
Signed-off-by: default avatarDuoming Zhou <duoming@zju.edu.cn>
Link: https://lore.kernel.org/r/20221002040709.27849-1-duoming@zju.edu.cn


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 72a59786

drivers/tty/n_gsm.c

+1 −1
Original line number Diff line number Diff line
@@ -1377,7 +1377,7 @@ static struct gsm_control *gsm_control_send(struct gsm_mux *gsm, 
		unsigned int command, u8 *data, int clen)

{

	struct gsm_control *ctrl = kzalloc(sizeof(struct gsm_control),

						GFP_KERNEL);

						GFP_ATOMIC);

	unsigned long flags;

	if (ctrl == NULL)

		return NULL;