diff options
| author | David Lamparter <equinox@diac24.net> | 2021-02-01 17:50:01 +0100 |
|---|---|---|
| committer | David Lamparter <equinox@diac24.net> | 2021-02-01 18:33:18 +0100 |
| commit | 738cca0ab4b900e2ecdb1ab28bc431fca014e6b0 (patch) | |
| tree | d831f56a74cfeac07a10b649cbfef149e3e6af82 | |
| parent | 6968b038ebb0beeda99b7ed70f3f1c35383f1ee3 (diff) | |
lib/printf: disable `%n` specifier
We don't use `%n` anywhere, so the only purpose it serves is enabling
exploits.
(I thought about this initially when adding printfrr, but I wasn't sure
we don't use `%n` anywhere, and thought I'll check later, and then just
forgot it...)
Signed-off-by: David Lamparter <equinox@diac24.net>
| -rw-r--r-- | lib/printf/printf-pos.c | 4 | ||||
| -rw-r--r-- | lib/printf/vfprintf.c | 6 |
2 files changed, 10 insertions, 0 deletions
diff --git a/lib/printf/printf-pos.c b/lib/printf/printf-pos.c index cc03f7ef9a..ac775bea4e 100644 --- a/lib/printf/printf-pos.c +++ b/lib/printf/printf-pos.c @@ -384,6 +384,7 @@ reswitch: switch (ch) { goto error; break; #endif /* !NO_FLOATING_POINT */ +#ifdef DANGEROUS_PERCENT_N case 'n': if (flags & INTMAXT) error = addtype(&types, TP_INTMAXT); @@ -404,6 +405,7 @@ reswitch: switch (ch) { if (error) goto error; continue; /* no output */ +#endif case 'O': flags |= LONGINT; /*FALLTHROUGH*/ @@ -576,6 +578,7 @@ reswitch: switch (ch) { goto error; break; #endif /* !NO_FLOATING_POINT */ +#ifdef DANGEROUS_PERCENT_N case 'n': if (flags & INTMAXT) error = addtype(&types, TP_INTMAXT); @@ -596,6 +599,7 @@ reswitch: switch (ch) { if (error) goto error; continue; /* no output */ +#endif case 'O': flags |= LONGINT; /*FALLTHROUGH*/ diff --git a/lib/printf/vfprintf.c b/lib/printf/vfprintf.c index 6ffccb3811..a0634cde4b 100644 --- a/lib/printf/vfprintf.c +++ b/lib/printf/vfprintf.c @@ -503,6 +503,11 @@ reswitch: switch (ch) { size = (prec >= 0) ? strnlen(cp, prec) : strlen(cp); sign = '\0'; break; +#ifdef DANGEROUS_PERCENT_N + /* FRR does not use %n in printf formats. This is just left + * here in case someone tries to use %n and starts debugging + * why the f* it doesn't work + */ case 'n': /* * Assignment-like behavior is specified if the @@ -526,6 +531,7 @@ reswitch: switch (ch) { else *GETARG(int *) = ret; continue; /* no output */ +#endif case 'O': flags |= LONGINT; /*FALLTHROUGH*/ |