On Mon, Apr 26, 2021 at 3:10 AM Florent Revest <revest@xxxxxxxxxxxx> wrote: > > On Sat, Apr 24, 2021 at 12:38 AM Andrii Nakryiko > <andrii.nakryiko@xxxxxxxxx> wrote: > > > > On Mon, Apr 19, 2021 at 8:52 AM Florent Revest <revest@xxxxxxxxxxxx> wrote: > > > > > > The "positive" part tests all format specifiers when things go well. > > > > > > The "negative" part makes sure that incorrect format strings fail at > > > load time. > > > > > > Signed-off-by: Florent Revest <revest@xxxxxxxxxxxx> > > > --- > > > .../selftests/bpf/prog_tests/snprintf.c | 125 ++++++++++++++++++ > > > .../selftests/bpf/progs/test_snprintf.c | 73 ++++++++++ > > > .../bpf/progs/test_snprintf_single.c | 20 +++ > > > 3 files changed, 218 insertions(+) > > > create mode 100644 tools/testing/selftests/bpf/prog_tests/snprintf.c > > > create mode 100644 tools/testing/selftests/bpf/progs/test_snprintf.c > > > create mode 100644 tools/testing/selftests/bpf/progs/test_snprintf_single.c > > > > > > diff --git a/tools/testing/selftests/bpf/prog_tests/snprintf.c b/tools/testing/selftests/bpf/prog_tests/snprintf.c > > > new file mode 100644 > > > index 000000000000..a958c22aec75 > > > --- /dev/null > > > +++ b/tools/testing/selftests/bpf/prog_tests/snprintf.c > > > @@ -0,0 +1,125 @@ > > > +// SPDX-License-Identifier: GPL-2.0 > > > +/* Copyright (c) 2021 Google LLC. */ > > > + > > > +#include <test_progs.h> > > > +#include "test_snprintf.skel.h" > > > +#include "test_snprintf_single.skel.h" > > > + > > > +#define EXP_NUM_OUT "-8 9 96 -424242 1337 DABBAD00" > > > +#define EXP_NUM_RET sizeof(EXP_NUM_OUT) > > > + > > > +#define EXP_IP_OUT "127.000.000.001 0000:0000:0000:0000:0000:0000:0000:0001" > > > +#define EXP_IP_RET sizeof(EXP_IP_OUT) > > > + > > > +/* The third specifier, %pB, depends on compiler inlining so don't check it */ > > > +#define EXP_SYM_OUT "schedule schedule+0x0/" > > > +#define MIN_SYM_RET sizeof(EXP_SYM_OUT) > > > + > > > +/* The third specifier, %p, is a hashed pointer which changes on every reboot */ > > > +#define EXP_ADDR_OUT "0000000000000000 ffff00000add4e55 " > > > +#define EXP_ADDR_RET sizeof(EXP_ADDR_OUT "unknownhashedptr") > > > + > > > +#define EXP_STR_OUT "str1 longstr" > > > +#define EXP_STR_RET sizeof(EXP_STR_OUT) > > > + > > > +#define EXP_OVER_OUT "%over" > > > +#define EXP_OVER_RET 10 > > > + > > > +#define EXP_PAD_OUT " 4 000" > > > > Roughly 50% of the time I get failure for this test case: > > > > test_snprintf_positive:FAIL:pad_out unexpected pad_out: actual ' 4 > > 0000' != expected ' 4 000' > > > > Re-running this test case immediately passes. Running again most > > probably fails. Please take a look. > > Do you have more information on how to reproduce this ? > I spinned up a VM at 87bd9e602 with ./vmtest -s and then run this script: > > #!/bin/sh > for i in `seq 1000` > do > ./test_progs -t snprintf > if [ $? -ne 0 ]; > then > echo FAILURE > exit 1 > fi > done > > The thousand executions passed. > > This is a bit concerning because your unexpected_pad_out seems to have > an extra '0' so it ends up with strlen(pad_out)=11 but > sizeof(pad_out)=10. The actual string writing is not really done by > our helper code but by the snprintf implementation (str and str_size > are only given to snprintf()) so I'd expect the truncation to work > well there. I'm a bit puzzled I'm puzzled too, have no idea. I also can't repro this with vmtest.sh. But I can quite reliably reproduce with my local ArchLinux-based qemu image with different config (see [0] for config itself). So please try with my config and see if that helps to repro. If not, I'll have to debug it on my own later. [0] https://gist.github.com/anakryiko/4b6ae21680842bdeacca8fa99d378048
