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author | Kees Cook <keescook@chromium.org> | 2013-11-14 22:31:58 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-11-15 00:32:20 (GMT) |
commit | 9196436ab2f713b823a2ba2024cb69f40b2f54a5 (patch) | |
tree | d10e292c5e307d616edfa13345a6735ed3cc93c9 /drivers/rtc/rtc-hid-sensor-time.c | |
parent | 652586df95e5d76b37d07a11839126dcfede1621 (diff) | |
download | linux-9196436ab2f713b823a2ba2024cb69f40b2f54a5.tar.xz |
vsprintf: ignore %n again
This ignores %n in printf again, as was originally documented.
Implementing %n poses a greater security risk than utility, so it should
stay ignored. To help anyone attempting to use %n, a warning will be
emitted if it is encountered.
Based on an earlier patch by Joe Perches.
Because %n was designed to write to pointers on the stack, it has been
frequently used as an attack vector when bugs are found that leak
user-controlled strings into functions that ultimately process format
strings. While this class of bug can still be turned into an
information leak, removing %n eliminates the common method of elevating
such a bug into an arbitrary kernel memory writing primitive,
significantly reducing the danger of this class of bug.
For seq_file users that need to know the length of a written string for
padding, please see seq_setwidth() and seq_pad() instead.
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Joe Perches <joe@perches.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/rtc/rtc-hid-sensor-time.c')
0 files changed, 0 insertions, 0 deletions