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| author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2023-11-06 17:25:40 -0300 |
|---|---|---|
| committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2023-11-21 16:15:42 -0300 |
| commit | 434eca873f14f618d6c2279b54fb809fb56f2c50 (patch) | |
| tree | 9894611373fc3fa1e0ba24d89df0b4767beefd19 /elf/dl-printf.c | |
| parent | 680c597e9c363bc74d1495b08f7a0593a80f8921 (diff) | |
| download | glibc-434eca873f14f618d6c2279b54fb809fb56f2c50.zip glibc-434eca873f14f618d6c2279b54fb809fb56f2c50.tar.gz glibc-434eca873f14f618d6c2279b54fb809fb56f2c50.tar.bz2 | |
elf: Fix _dl_debug_vdprintf to work before self-relocation
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).
For i386, _dl_writev with PIE requires to use the old 'int $0x80'
syscall mode because the calling the TLS register (gs) is not yet
initialized.
Checked on x86_64-linux-gnu.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Diffstat (limited to 'elf/dl-printf.c')
| -rw-r--r-- | elf/dl-printf.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/elf/dl-printf.c b/elf/dl-printf.c index 6efb4c0..5e93208 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; |