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| author | Daniel Borkmann <daniel@iogearbox.net> | 2024-09-13 21:17:50 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2024-09-13 22:17:56 +0200 |
| commit | 4b3786a6c5397dc220b1483d8e2f4867743e966f (patch) | |
| tree | 7d2f88cfa877670245a0dd75fc261ba6bdbb2a10 /kernel/bpf/helpers.c | |
| parent | bpf: Improve check_raw_mode_ok test for MEM_UNINIT-tagged types (diff) | |
| download | linux-4b3786a6c5397dc220b1483d8e2f4867743e966f.tar.xz linux-4b3786a6c5397dc220b1483d8e2f4867743e966f.zip | |
bpf: Zero former ARG_PTR_TO_{LONG,INT} args in case of error
For all non-tracing helpers which formerly had ARG_PTR_TO_{LONG,INT} as input
arguments, zero the value for the case of an error as otherwise it could leak
memory. For tracing, it is not needed given CAP_PERFMON can already read all
kernel memory anyway hence bpf_get_func_arg() and bpf_get_func_ret() is skipped
in here.
Also, the MTU helpers mtu_len pointer value is being written but also read.
Technically, the MEM_UNINIT should not be there in order to always force init.
Removing MEM_UNINIT needs more verifier rework though: MEM_UNINIT right now
implies two things actually: i) write into memory, ii) memory does not have
to be initialized. If we lift MEM_UNINIT, it then becomes: i) read into memory,
ii) memory must be initialized. This means that for bpf_*_check_mtu() we're
readding the issue we're trying to fix, that is, it would then be able to
write back into things like .rodata BPF maps. Follow-up work will rework the
MEM_UNINIT semantics such that the intent can be better expressed. For now
just clear the *mtu_len on error path which can be lifted later again.
Fixes: 8a67f2de9b1d ("bpf: expose bpf_strtol and bpf_strtoul to all program types")
Fixes: d7a4cb9b6705 ("bpf: Introduce bpf_strtol and bpf_strtoul helpers")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/e5edd241-59e7-5e39-0ee5-a51e31b6840a@iogearbox.net
Link: https://lore.kernel.org/r/20240913191754.13290-5-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf/helpers.c')
| -rw-r--r-- | kernel/bpf/helpers.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 5e97fdc6b20f..1a43d06eab28 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -523,6 +523,7 @@ BPF_CALL_4(bpf_strtol, const char *, buf, size_t, buf_len, u64, flags, long long _res; int err; + *res = 0; err = __bpf_strtoll(buf, buf_len, flags, &_res); if (err < 0) return err; @@ -548,6 +549,7 @@ BPF_CALL_4(bpf_strtoul, const char *, buf, size_t, buf_len, u64, flags, bool is_negative; int err; + *res = 0; err = __bpf_strtoull(buf, buf_len, flags, &_res, &is_negative); if (err < 0) return err; |