• Jean Delvare's avatar
    firmware: dmi_scan: Fix handling of empty DMI strings · a7770ae1
    Jean Delvare authored
    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: default avatarJean Delvare <jdelvare@suse.de>
    Fixes: 79da4721 ("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>
    a7770ae1
dmi_scan.c 26.1 KB