diff options
author | Laszlo Ersek <lersek@redhat.com> | 2016-04-21 16:21:11 (GMT) |
---|---|---|
committer | Matt Fleming <matt@codeblueprint.co.uk> | 2016-04-22 18:41:41 (GMT) |
commit | 630ba0cc7a6dbafbdee43795617c872b35cde1b4 (patch) | |
tree | 0dbc30e47cd62af70ac76630074d4a0d9c8581ff /drivers/firmware/efi | |
parent | c3b46c73264b03000d1e18b22f5caf63332547c9 (diff) | |
download | linux-630ba0cc7a6dbafbdee43795617c872b35cde1b4.tar.xz |
efi: Fix out-of-bounds read in variable_matches()
The variable_matches() function can currently read "var_name[len]", for
example when:
- var_name[0] == 'a',
- len == 1
- match_name points to the NUL-terminated string "ab".
This function is supposed to accept "var_name" inputs that are not
NUL-terminated (hence the "len" parameter"). Document the function, and
access "var_name[*match]" only if "*match" is smaller than "len".
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Cc: Peter Jones <pjones@redhat.com>
Cc: Matthew Garrett <mjg59@coreos.com>
Cc: Jason Andryuk <jandryuk@gmail.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: <stable@vger.kernel.org> # v3.10+
Link: http://thread.gmane.org/gmane.comp.freedesktop.xorg.drivers.intel/86906
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Diffstat (limited to 'drivers/firmware/efi')
-rw-r--r-- | drivers/firmware/efi/vars.c | 37 |
1 files changed, 26 insertions, 11 deletions
diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c index 0ac594c..34b7419 100644 --- a/drivers/firmware/efi/vars.c +++ b/drivers/firmware/efi/vars.c @@ -202,29 +202,44 @@ static const struct variable_validate variable_validate[] = { { NULL_GUID, "", NULL }, }; +/* + * Check if @var_name matches the pattern given in @match_name. + * + * @var_name: an array of @len non-NUL characters. + * @match_name: a NUL-terminated pattern string, optionally ending in "*". A + * final "*" character matches any trailing characters @var_name, + * including the case when there are none left in @var_name. + * @match: on output, the number of non-wildcard characters in @match_name + * that @var_name matches, regardless of the return value. + * @return: whether @var_name fully matches @match_name. + */ static bool variable_matches(const char *var_name, size_t len, const char *match_name, int *match) { for (*match = 0; ; (*match)++) { char c = match_name[*match]; - char u = var_name[*match]; - /* Wildcard in the matching name means we've matched */ - if (c == '*') + switch (c) { + case '*': + /* Wildcard in @match_name means we've matched. */ return true; - /* Case sensitive match */ - if (!c && *match == len) - return true; + case '\0': + /* @match_name has ended. Has @var_name too? */ + return (*match == len); - if (c != u) + default: + /* + * We've reached a non-wildcard char in @match_name. + * Continue only if there's an identical character in + * @var_name. + */ + if (*match < len && c == var_name[*match]) + continue; return false; - - if (!c) - return true; + } } - return true; } bool |