[flashrom] [Security Announcement] fscanf format string security bug in flashrom layout code

[Carl-Daniel Hailfinger]

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An internal security audit of the flashrom project by
Carl-Daniel Hailfinger found a buffer overflow bug present in all
flashrom versions since the year 2005.
This bug was independently found and reported to flashrom.org by
Cosmin Gorgovan a few days ago.

A buffer on the stack and a buffer on the heap are affected by the
overflow caused by an incorrect fscanf format string.
The buffer overflow can only be triggered if the optional layout feature
is used and if the user manually specifies a specially crafted layout
file on the command line. Command line parsing and flash image handling
do not trigger the buggy code path.
Most usage of flashrom does not involve layout files.

The fix in this commit (changed fscanf format string) can be applied to
layout.c of all past flashrom versions.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net>
Acked-by: Stefan Tauner <stefan.tauner at alumni.tuwien.ac.at>

Index: flashrom-parserbugs_simple/layout.c
===================================================================
--- flashrom-parserbugs_simple/layout.c	(revision 1952)
+++ flashrom-parserbugs_simple/layout.c	(working copy)
@@ -68,7 +68,7 @@
 			(void)fclose(romlayout);
 			return 1;
 		}
-		if (2 != fscanf(romlayout, "%s %s\n", tempstr, rom_entries[num_rom_entries].name))
+		if (2 != fscanf(romlayout, "%255s %255s\n", tempstr, rom_entries[num_rom_entries].name))
 			continue;
 #if 0
 		// fscanf does not like arbitrary comments like that :( later

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