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authorJean Delvare <jdelvare@suse.de>2018-02-03 13:25:20 +0300
committerJean Delvare <jdelvare@suse.de>2018-02-03 13:25:20 +0300
commita7770ae194569e96a93c48aceb304edded9cc648 (patch)
tree90cb465ea86fb1f3c455b90e1f71739511bb735a /drivers/firmware
parent7117794feb1602ea5efca1c7bfd5b78c3278d29d (diff)
downloadlinux-a7770ae194569e96a93c48aceb304edded9cc648.tar.xz
firmware: dmi_scan: Fix handling of empty DMI strings
The handling of empty DMI strings looks quite broken to me: * Strings from 1 to 7 spaces are not considered empty. * True empty DMI strings (string index set to 0) are not considered empty, and result in allocating a 0-char string. * Strings with invalid index also result in allocating a 0-char string. * Strings starting with 8 spaces are all considered empty, even if non-space characters follow (sounds like a weird thing to do, but I have actually seen occurrences of this in DMI tables before.) * Strings which are considered empty are reported as 8 spaces, instead of being actually empty. Some of these issues are the result of an off-by-one error in memcmp, the rest is incorrect by design. So let's get it square: missing strings and strings made of only spaces, regardless of their length, should be treated as empty and no memory should be allocated for them. All other strings are non-empty and should be allocated. Signed-off-by: Jean Delvare <jdelvare@suse.de> Fixes: 79da4721117f ("x86: fix DMI out of memory problems") Cc: Parag Warudkar <parag.warudkar@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'drivers/firmware')
-rw-r--r--drivers/firmware/dmi_scan.c22
1 files changed, 9 insertions, 13 deletions
diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 8cd5db6691b2..a7072e7880ee 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -18,7 +18,7 @@ EXPORT_SYMBOL_GPL(dmi_kobj);
* of and an antecedent to, SMBIOS, which stands for System
* Management BIOS. See further: http://www.dmtf.org/standards
*/
-static const char dmi_empty_string[] = " ";
+static const char dmi_empty_string[] = "";
static u32 dmi_ver __initdata;
static u32 dmi_len;
@@ -39,25 +39,21 @@ static int dmi_memdev_nr;
static const char * __init dmi_string_nosave(const struct dmi_header *dm, u8 s)
{
const u8 *bp = ((u8 *) dm) + dm->length;
+ const u8 *nsp;
if (s) {
- s--;
- while (s > 0 && *bp) {
+ while (--s > 0 && *bp)
bp += strlen(bp) + 1;
- s--;
- }
-
- if (*bp != 0) {
- size_t len = strlen(bp)+1;
- size_t cmp_len = len > 8 ? 8 : len;
- if (!memcmp(bp, dmi_empty_string, cmp_len))
- return dmi_empty_string;
+ /* Strings containing only spaces are considered empty */
+ nsp = bp;
+ while (*nsp == ' ')
+ nsp++;
+ if (*nsp != '\0')
return bp;
- }
}
- return "";
+ return dmi_empty_string;
}
static const char * __init dmi_string(const struct dmi_header *dm, u8 s)