[PATCH 3.17 075/122] of: Fix crash if an earlycon driver is not found

From: Greg Kroah-Hartman
Date: Fri Dec 05 2014 - 17:50:59 EST

3.17-stable review patch. If anyone has any objections, please let me know.


From: Kevin Cernekee <cernekee@xxxxxxxxx>

commit ab74d00a39f70e1bc34a01322bb59f3750ca7a8c upstream.

__earlycon_of_table_sentinel.compatible is a char[128], not a pointer, so
it will never be NULL. Checking it against NULL causes the match loop to
run past the end of the array, and eventually match a bogus entry, under
the following conditions:

- Kernel command line specifies "earlycon" with no parameters
- DT has a stdout-path pointing to a UART node
- The UART driver doesn't use OF_EARLYCON_DECLARE (or maybe the console
driver is compiled out)

Fix this by checking to see if match->compatible is a non-empty string.

Signed-off-by: Kevin Cernekee <cernekee@xxxxxxxxx>
Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/of/fdt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -773,7 +773,7 @@ int __init early_init_dt_scan_chosen_ser
if (offset < 0)
return -ENODEV;

- while (match->compatible) {
+ while (match->compatible[0]) {
unsigned long addr;
if (fdt_node_check_compatible(fdt, offset, match->compatible)) {

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