Commit 407f666d authored by John Ogness's avatar John Ogness Committed by Petr Mladek
Browse files

printk_ringbuffer: Add sanity check for 0-size data 



get_data() has a sanity check for regular data blocks to ensure at
least space for the ID exists. But a regular block should also have
at least 1 byte of data (otherwise it would be data-less instead of
regular).

Expand the get_data() block size sanity check to additionally expect
at least 1 byte of data.

Signed-off-by: default avatarJohn Ogness <john.ogness@linutronix.de>
Reviewed-by: default avatarPetr Mladek <pmladek@suse.com>
Tested-by: default avatarPetr Mladek <pmladek@suse.com>
Link: https://patch.msgid.link/20260326133809.8045-2-john.ogness@linutronix.de


Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
parent 8e81ecbf

kernel/printk/printk_ringbuffer.c

+5 −2
Original line number Diff line number Diff line
@@ -1308,8 +1308,11 @@ static const char *get_data(struct prb_data_ring *data_ring, 
		return NULL;

	}



	/* A valid data block will always have at least an ID. */

	if (WARN_ON_ONCE(*data_size < sizeof(db->id)))

	/*

	 * A regular data block will always have an ID and at least

	 * 1 byte of data. Data-less blocks were handled earlier.

	 */

	if (WARN_ON_ONCE(*data_size <= sizeof(db->id)))

		return NULL;



	/* Subtract block ID space from size to reflect data size. */