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author | Jean Delvare <jdelvare@suse.de> | 2018-02-03 11:25:20 +0100 |
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committer | Jean Delvare <jdelvare@suse.de> | 2018-02-03 11:25:20 +0100 |
commit | a7770ae194569e96a93c48aceb304edded9cc648 (patch) | |
tree | 90cb465ea86fb1f3c455b90e1f71739511bb735a /drivers/firmware/dmi_scan.c | |
parent | 7117794feb1602ea5efca1c7bfd5b78c3278d29d (diff) | |
download | linux-a7770ae194569e96a93c48aceb304edded9cc648.tar.gz linux-a7770ae194569e96a93c48aceb304edded9cc648.tar.bz2 linux-a7770ae194569e96a93c48aceb304edded9cc648.zip |
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/dmi_scan.c')
-rw-r--r-- | drivers/firmware/dmi_scan.c | 22 |
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) |