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* [PATCH v2] efifb: prevent null-deref when iterating dmi_list
@ 2013-10-02 16:40 ` David Herrmann
  0 siblings, 0 replies; 16+ messages in thread
From: David Herrmann @ 2013-10-02 16:40 UTC (permalink / raw)
  To: linux-fbdev
  Cc: James Bates, linux-kernel, Tomi Valkeinen,
	Jean-Christophe Plagniol-Villard, David Herrmann, James Bates

The dmi_list array is initialized using gnu designated initializers, and
therefore may contain fewer explicitly defined entries as there are
elements in it. This is because the enum above with M_xyz constants
contains more items than the designated initializer. Those elements not
explicitly initialized are implicitly set to 0.

Now efifb_setup() loops through all these array elements, and performs
a strcmp on each item. For non explicitly initialized elements this will
be a null pointer:

This patch swaps the check order in the if statement, thus checks first
whether dmi_list[i].base is null.

Signed-off-by: James Bates <james.h.bates@yahoo.com>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
---
Hi

As James didn't respond to the last emails, I just rebased the patch and resent
it. The efi M_xyz constants were moved to x86-sysfb so if anyone wants to remove
unused bits, please send a separate patch to LKML and x86-ML. This patch just
fixes the NULL-deref.

Thanks
David

 drivers/video/efifb.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/video/efifb.c b/drivers/video/efifb.c
index 7f9ff75..fcb9500 100644
--- a/drivers/video/efifb.c
+++ b/drivers/video/efifb.c
@@ -108,8 +108,8 @@ static int efifb_setup(char *options)
 			if (!*this_opt) continue;
 
 			for (i = 0; i < M_UNKNOWN; i++) {
-				if (!strcmp(this_opt, efifb_dmi_list[i].optname) &&
-				    efifb_dmi_list[i].base != 0) {
+				if (efifb_dmi_list[i].base != 0 &&
+				    !strcmp(this_opt, efifb_dmi_list[i].optname)) {
 					screen_info.lfb_base = efifb_dmi_list[i].base;
 					screen_info.lfb_linelength = efifb_dmi_list[i].stride;
 					screen_info.lfb_width = efifb_dmi_list[i].width;
-- 
1.8.4


^ permalink raw reply related	[flat|nested] 16+ messages in thread

end of thread, other threads:[~2013-11-01 12:09 UTC | newest]

Thread overview: 16+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2013-10-02 16:40 [PATCH v2] efifb: prevent null-deref when iterating dmi_list David Herrmann
2013-10-02 16:40 ` David Herrmann
2013-10-02 16:43 ` [PATCH v3] " David Herrmann
2013-10-02 16:43   ` David Herrmann
2013-10-19 10:40   ` David Herrmann
2013-10-19 10:40     ` David Herrmann
2013-10-29 10:42   ` Tomi Valkeinen
2013-10-29 10:42     ` Tomi Valkeinen
2013-10-31 10:45 ` [PATCH v2] " Jean-Christophe PLAGNIOL-VILLARD
2013-10-31 10:45   ` Jean-Christophe PLAGNIOL-VILLARD
2013-10-31 16:17   ` David Herrmann
2013-10-31 16:17     ` David Herrmann
2013-11-01 11:10     ` Jean-Christophe PLAGNIOL-VILLARD
2013-11-01 11:10       ` Jean-Christophe PLAGNIOL-VILLARD
2013-11-01 12:09       ` David Herrmann
2013-11-01 12:09         ` David Herrmann

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