| Message ID | 20221229125802.2715435-2-adhemerval.zanella@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | Fix remaining -Os/-O1 compile issues [BZ #19444] | expand |
On 12/29/22 07:57, Adhemerval Zanella via Libc-alpha wrote: > The buffer used by snprintf might not be large enough for all possible > inputs, as indicated by gcc with -O1: > > ../locale/programs/linereader.c: In function ‘utf8_sequence_error’: > ../locale/programs/linereader.c:713:58: error: ‘%02x’ directive output > may be truncated writing between 2 and 8 bytes into a region of size > between 1 and 13 [-Werror=format-truncation=] > 713 | snprintf (buf, sizeof (buf), "0x%02x 0x%02x 0x%02x 0x%02x", > | ^~~~ > ../locale/programs/linereader.c:713:34: note: directive argument in the > range [0, 2147483647] > 713 | snprintf (buf, sizeof (buf), "0x%02x 0x%02x 0x%02x 0x%02x", > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > ../locale/programs/linereader.c:713:5: note: ‘snprintf’ output between > 20 and 38 bytes into a destination of size 30 > 713 | snprintf (buf, sizeof (buf), "0x%02x 0x%02x 0x%02x 0x%02x", > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > 714 | ch1, ch2, ch3, ch4); > | ~~~~~~~~~~~~~~~~~~~ > > Checked on x86_64-linux-gnu. LGTM. Took me a minute to work out the 38 bytes value though. Reviewed-by: Carlos O'Donell <carlos@redhat.com> > --- > locale/programs/linereader.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/locale/programs/linereader.c b/locale/programs/linereader.c > index 0460074a0c..794f25a6e4 100644 > --- a/locale/programs/linereader.c > +++ b/locale/programs/linereader.c > @@ -701,7 +701,7 @@ static bool > utf8_sequence_error (struct linereader *lr, uint8_t ch1, int ch2, int ch3, > int ch4) > { > - char buf[30]; > + char buf[38]; OK. "0x7f 0x7fffffff 0x7fffffff 0x7fffffff\0" = 4 + 1 + 10 + 1 + 10 + 1 + 10 + 1 = 38 bytes including null terminator. I expect that at -O2 that VRP can see the values propagated from utf8_decode and determine the buffer will be smaller by a lot given the range checks. The ch2, ch3, and ch4 values shall not exceed 0xff in all cases since they are all distinct bytes in the UTF-8 sequence. I expect that the worst case is actually "0xff 0xff 0xff 0xff\0" or 20 bytes, but if the checks in utf8_decode are changed then the worst case could be 38 bytes. > > if (ch2 < 0) > snprintf (buf, sizeof (buf), "0x%02x", ch1);
diff --git a/locale/programs/linereader.c b/locale/programs/linereader.c index 0460074a0c..794f25a6e4 100644 --- a/locale/programs/linereader.c +++ b/locale/programs/linereader.c @@ -701,7 +701,7 @@ static bool utf8_sequence_error (struct linereader *lr, uint8_t ch1, int ch2, int ch3, int ch4) { - char buf[30]; + char buf[38]; if (ch2 < 0) snprintf (buf, sizeof (buf), "0x%02x", ch1);
The buffer used by snprintf might not be large enough for all possible inputs, as indicated by gcc with -O1: ../locale/programs/linereader.c: In function ‘utf8_sequence_error’: ../locale/programs/linereader.c:713:58: error: ‘%02x’ directive output may be truncated writing between 2 and 8 bytes into a region of size between 1 and 13 [-Werror=format-truncation=] 713 | snprintf (buf, sizeof (buf), "0x%02x 0x%02x 0x%02x 0x%02x", | ^~~~ ../locale/programs/linereader.c:713:34: note: directive argument in the range [0, 2147483647] 713 | snprintf (buf, sizeof (buf), "0x%02x 0x%02x 0x%02x 0x%02x", | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ../locale/programs/linereader.c:713:5: note: ‘snprintf’ output between 20 and 38 bytes into a destination of size 30 713 | snprintf (buf, sizeof (buf), "0x%02x 0x%02x 0x%02x 0x%02x", | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 714 | ch1, ch2, ch3, ch4); | ~~~~~~~~~~~~~~~~~~~ Checked on x86_64-linux-gnu. --- locale/programs/linereader.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)