| Message ID | 20231017130526.2216827-8-adhemerval.zanella@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | Improve loader environment variable handling | expand |
On 2023-10-17 09:05, Adhemerval Zanella wrote: > The strlen might trigger and invalid GOT entry if it used before > the process is self-relocated (for instance on dl-tunables if any > error occurs). > > Checked on x86_64-linux-gnu. > --- LGTM. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org> > elf/dl-printf.c | 16 ++++++++++++++-- > stdio-common/Makefile | 5 +++++ > stdio-common/_itoa.c | 5 +++++ > 3 files changed, 24 insertions(+), 2 deletions(-) > > diff --git a/elf/dl-printf.c b/elf/dl-printf.c > index 6efb4c019a..5e93208535 100644 > --- a/elf/dl-printf.c > +++ b/elf/dl-printf.c > @@ -17,6 +17,10 @@ > License along with the GNU C Library; if not, see > <https://www.gnu.org/licenses/>. */ > > +#include <string.h> > +#if BUILD_PIE_DEFAULT > +# pragma GCC visibility push(hidden) > +#endif > #include <_itoa.h> > #include <assert.h> > #include <dl-writev.h> > @@ -25,11 +29,19 @@ > #include <stdarg.h> > #include <stdint.h> > #include <stdlib.h> > -#include <string.h> > #include <sys/uio.h> > #include <unistd.h> > #include <intprops.h> > > +/* The function might be called before the process is self-relocated. */ > +static size_t > +_dl_debug_strlen (const char *s) > +{ > + const char *p = s; > + for (; *s != '\0'; s++); > + return s - p; > +} > + > /* Bare-bones printf implementation. This function only knows about > the formats and flags needed and can handle only up to 64 stripes in > the output. */ > @@ -193,7 +205,7 @@ _dl_debug_vdprintf (int fd, int tag_p, const char *fmt, va_list arg) > case 's': > /* Get the string argument. */ > iov[niov].iov_base = va_arg (arg, char *); > - iov[niov].iov_len = strlen (iov[niov].iov_base); > + iov[niov].iov_len = _dl_debug_strlen (iov[niov].iov_base); > if (prec != -1) > iov[niov].iov_len = MIN ((size_t) prec, iov[niov].iov_len); > ++niov; > diff --git a/stdio-common/Makefile b/stdio-common/Makefile > index bacb795fed..e88a9cea29 100644 > --- a/stdio-common/Makefile > +++ b/stdio-common/Makefile > @@ -460,6 +460,11 @@ CFLAGS-isoc23_scanf.c += -fexceptions > > CFLAGS-dprintf.c += $(config-cflags-wno-ignored-attributes) > > +# Called during static library initialization, so turn stack-protection > +# off for non-shared builds. > +CFLAGS-_itoa.o = $(no-stack-protector) > +CFLAGS-_itoa.op = $(no-stack-protector) > + > # scanf18.c and scanf19.c test a deprecated extension which is no > # longer visible under most conformance levels; see the source files > # for more detail. > diff --git a/stdio-common/_itoa.c b/stdio-common/_itoa.c > index 3037b0f529..48f2903ecb 100644 > --- a/stdio-common/_itoa.c > +++ b/stdio-common/_itoa.c > @@ -16,6 +16,11 @@ > License along with the GNU C Library; if not, see > <https://www.gnu.org/licenses/>. */ > > +/* Mark symbols hidden in static PIE for early self relocation to work. > + Note: string.h may have ifuncs which cannot be hidden on i686. */ > +#if BUILD_PIE_DEFAULT > +# pragma GCC visibility push(hidden) > +#endif > #include <gmp-mparam.h> > #include <gmp.h> > #include <limits.h>
diff --git a/elf/dl-printf.c b/elf/dl-printf.c index 6efb4c019a..5e93208535 100644 --- a/elf/dl-printf.c +++ b/elf/dl-printf.c @@ -17,6 +17,10 @@ License along with the GNU C Library; if not, see <https://www.gnu.org/licenses/>. */ +#include <string.h> +#if BUILD_PIE_DEFAULT +# pragma GCC visibility push(hidden) +#endif #include <_itoa.h> #include <assert.h> #include <dl-writev.h> @@ -25,11 +29,19 @@ #include <stdarg.h> #include <stdint.h> #include <stdlib.h> -#include <string.h> #include <sys/uio.h> #include <unistd.h> #include <intprops.h> +/* The function might be called before the process is self-relocated. */ +static size_t +_dl_debug_strlen (const char *s) +{ + const char *p = s; + for (; *s != '\0'; s++); + return s - p; +} + /* Bare-bones printf implementation. This function only knows about the formats and flags needed and can handle only up to 64 stripes in the output. */ @@ -193,7 +205,7 @@ _dl_debug_vdprintf (int fd, int tag_p, const char *fmt, va_list arg) case 's': /* Get the string argument. */ iov[niov].iov_base = va_arg (arg, char *); - iov[niov].iov_len = strlen (iov[niov].iov_base); + iov[niov].iov_len = _dl_debug_strlen (iov[niov].iov_base); if (prec != -1) iov[niov].iov_len = MIN ((size_t) prec, iov[niov].iov_len); ++niov; diff --git a/stdio-common/Makefile b/stdio-common/Makefile index bacb795fed..e88a9cea29 100644 --- a/stdio-common/Makefile +++ b/stdio-common/Makefile @@ -460,6 +460,11 @@ CFLAGS-isoc23_scanf.c += -fexceptions CFLAGS-dprintf.c += $(config-cflags-wno-ignored-attributes) +# Called during static library initialization, so turn stack-protection +# off for non-shared builds. +CFLAGS-_itoa.o = $(no-stack-protector) +CFLAGS-_itoa.op = $(no-stack-protector) + # scanf18.c and scanf19.c test a deprecated extension which is no # longer visible under most conformance levels; see the source files # for more detail. diff --git a/stdio-common/_itoa.c b/stdio-common/_itoa.c index 3037b0f529..48f2903ecb 100644 --- a/stdio-common/_itoa.c +++ b/stdio-common/_itoa.c @@ -16,6 +16,11 @@ License along with the GNU C Library; if not, see <https://www.gnu.org/licenses/>. */ +/* Mark symbols hidden in static PIE for early self relocation to work. + Note: string.h may have ifuncs which cannot be hidden on i686. */ +#if BUILD_PIE_DEFAULT +# pragma GCC visibility push(hidden) +#endif #include <gmp-mparam.h> #include <gmp.h> #include <limits.h>