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Commit e945325e authored by He Zhe's avatar He Zhe Committed by Greg Kroah-Hartman
Browse files

printk: Fix panic caused by passing log_buf_len to command line 

commit 277fcdb2cfee38ccdbe07e705dbd4896ba0c9930 upstream.

log_buf_len_setup does not check input argument before passing it to
simple_strtoull. The argument would be a NULL pointer if "log_buf_len",
without its value, is set in command line and thus causes the following
panic.

PANIC: early exception 0xe3 IP 10:ffffffffaaeacd0d error 0 cr2 0x0
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.19.0-rc4-yocto-standard+ #1
[    0.000000] RIP: 0010:_parse_integer_fixup_radix+0xd/0x70
...
[    0.000000] Call Trace:
[    0.000000]  simple_strtoull+0x29/0x70
[    0.000000]  memparse+0x26/0x90
[    0.000000]  log_buf_len_setup+0x17/0x22
[    0.000000]  do_early_param+0x57/0x8e
[    0.000000]  parse_args+0x208/0x320
[    0.000000]  ? rdinit_setup+0x30/0x30
[    0.000000]  parse_early_options+0x29/0x2d
[    0.000000]  ? rdinit_setup+0x30/0x30
[    0.000000]  parse_early_param+0x36/0x4d
[    0.000000]  setup_arch+0x336/0x99e
[    0.000000]  start_kernel+0x6f/0x4ee
[    0.000000]  x86_64_start_reservations+0x24/0x26
[    0.000000]  x86_64_start_kernel+0x6f/0x72
[    0.000000]  secondary_startup_64+0xa4/0xb0

This patch adds a check to prevent the panic.

Link: http://lkml.kernel.org/r/1538239553-81805-1-git-send-email-zhe.he@windriver.com


Cc: stable@vger.kernel.org
Cc: rostedt@goodmis.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarHe Zhe <zhe.he@windriver.com>
Reviewed-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 93e2e867

kernel/printk/printk.c

+6 −1
Original line number Diff line number Diff line
@@ -1048,7 +1048,12 @@ static void __init log_buf_len_update(unsigned size) 
/* save requested log_buf_len since it's too early to process it */

static int __init log_buf_len_setup(char *str)

{

	unsigned size = memparse(str, &str);

	unsigned int size;



	if (!str)

		return -EINVAL;



	size = memparse(str, &str);



	log_buf_len_update(size);