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Revision da094e42848e3c36feaa3b5271e53983fd45424f authored by Prakash Gupta on 18 August 2017, 22:16:21 UTC, committed by Linus Torvalds on 18 August 2017, 22:32:02 UTC 
mm/cma_debug.c: fix stack corruption due to sprintf usage
 
name[] in cma_debugfs_add_one() can only accommodate 16 chars including
NULL to store sprintf output.  It's common for cma device name to be
larger than 15 chars.  This can cause stack corrpution.  If the gcc
stack protector is turned on, this can cause a panic due to stack
corruption.

Below is one example trace:

  Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in:
  ffffff8e69a75730
  Call trace:
     dump_backtrace+0x0/0x2c4
     show_stack+0x20/0x28
     dump_stack+0xb8/0xf4
     panic+0x154/0x2b0
     print_tainted+0x0/0xc0
     cma_debugfs_init+0x274/0x290
     do_one_initcall+0x5c/0x168
     kernel_init_freeable+0x1c8/0x280

Fix the short sprintf buffer in cma_debugfs_add_one() by using
scnprintf() instead of sprintf().

Link: http://lkml.kernel.org/r/1502446217-21840-1-git-send-email-guptap@codeaurora.org
Fixes: f318dd083c81 ("cma: Store a name in the cma structure")
Signed-off-by: Prakash Gupta <guptap@codeaurora.org>
Acked-by: Laura Abbott <labbott@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent eb61b59
Raw File
trace.h 
#ifndef _LINUX_TRACE_H
#define _LINUX_TRACE_H

#ifdef CONFIG_TRACING
/*
 * The trace export - an export of Ftrace output. The trace_export
 * can process traces and export them to a registered destination as
 * an addition to the current only output of Ftrace - i.e. ring buffer.
 *
 * If you want traces to be sent to some other place rather than ring
 * buffer only, just need to register a new trace_export and implement
 * its own .write() function for writing traces to the storage.
 *
 * next		- pointer to the next trace_export
 * write	- copy traces which have been delt with ->commit() to
 *		  the destination
 */
struct trace_export {
	struct trace_export __rcu	*next;
	void (*write)(const void *, unsigned int);
};

int register_ftrace_export(struct trace_export *export);
int unregister_ftrace_export(struct trace_export *export);

#endif	/* CONFIG_TRACING */

#endif	/* _LINUX_TRACE_H */
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