Re: [PATCH v2] efifb: prevent null-deref when iterating dmi_list
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From: Jean-Christophe PLAGNIOL-VILLARD <hidden>
Date: 2013-10-31 10:43:56
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On 18:40 Wed 02 Oct , David Herrmann wrote:
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 <redacted> Signed-off-by: David Herrmann <redacted>
with the simpleDRM arriving next merge I'm wondering if we need to keep it? Best Regaards, J.
quoted hunk ↗ jump to hunk
--- 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