tty: n_gsm: Debug output allocation must use GFP_ATOMIC

BugLink: https://bugs.launchpad.net/bugs/1983149
commit e74024b2eccbb784824a0f9feaeaaa3b47514b79 upstream.

Dan Carpenter <dan.carpenter@oracle.com> reported the following Smatch
warning:

drivers/tty/n_gsm.c:720 gsm_data_kick()
warn: sleeping in atomic context

This is because gsm_control_message() is holding a spin lock so
gsm_hex_dump_bytes() needs to use GFP_ATOMIC instead of GFP_KERNEL.

Fixes: 925ea0fa5277 ("tty: n_gsm: Fix packet data hex dump output")
Cc: stable <stable@kernel.org>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20220523155052.57129-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index a246f429ffb7d6f2d291c239e797c70e863c34b3..6734ef22c304a214fc9d806216fce71725e3e80b 100644 (file)
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -454,7 +454,7 @@ static void gsm_hex_dump_bytes(const char *fname, const u8 *data,
                return;
        }
 
-       prefix = kasprintf(GFP_KERNEL, "%s: ", fname);
+       prefix = kasprintf(GFP_ATOMIC, "%s: ", fname);
        if (!prefix)
                return;
        print_hex_dump(KERN_INFO, prefix, DUMP_PREFIX_OFFSET, 16, 1, data, len,