This is a note to let you know that I've just added the patch titled
bpf: Do cleanup in bpf_bprintf_cleanup only when needed
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bpf-do-cleanup-in-bpf_bprintf_cleanup-only-when-needed.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From stable+bounces-20401-greg=kroah.com@xxxxxxxxxxxxxxx Sat Feb 17 13:13:54 2024
From: Thadeu Lima de Souza Cascardo <cascardo@xxxxxxxxxx>
Date: Sat, 17 Feb 2024 09:13:20 -0300
Subject: bpf: Do cleanup in bpf_bprintf_cleanup only when needed
To: stable@xxxxxxxxxxxxxxx
Cc: cascardo@xxxxxxxxxx, jolsa@xxxxxxxxxx, daniel@xxxxxxxxxxxxx, yhs@xxxxxx
Message-ID: <20240217121321.2045993-7-cascardo@xxxxxxxxxx>
From: Jiri Olsa <jolsa@xxxxxxxxxx>
commit f19a4050455aad847fb93f18dc1fe502eb60f989 upstream.
Currently we always cleanup/decrement bpf_bprintf_nest_level variable
in bpf_bprintf_cleanup if it's > 0.
There's possible scenario where this could cause a problem, when
bpf_bprintf_prepare does not get bin_args buffer (because num_args is 0)
and following bpf_bprintf_cleanup call decrements bpf_bprintf_nest_level
variable, like:
in task context:
bpf_bprintf_prepare(num_args != 0) increments 'bpf_bprintf_nest_level = 1'
-> first irq :
bpf_bprintf_prepare(num_args == 0)
bpf_bprintf_cleanup decrements 'bpf_bprintf_nest_level = 0'
-> second irq:
bpf_bprintf_prepare(num_args != 0) bpf_bprintf_nest_level = 1
gets same buffer as task context above
Adding check to bpf_bprintf_cleanup and doing the real cleanup only if we
got bin_args data in the first place.
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Acked-by: Yonghong Song <yhs@xxxxxx>
Link: https://lore.kernel.org/bpf/20221215214430.1336195-3-jolsa@xxxxxxxxxx
[cascardo: there is no bpf_trace_vprintk in 5.15]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/bpf.h | 2 +-
kernel/bpf/helpers.c | 16 +++++++++-------
kernel/trace/bpf_trace.c | 4 ++--
3 files changed, 12 insertions(+), 10 deletions(-)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2299,6 +2299,6 @@ struct bpf_bprintf_data {
int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
u32 num_args, struct bpf_bprintf_data *data);
-void bpf_bprintf_cleanup(void);
+void bpf_bprintf_cleanup(struct bpf_bprintf_data *data);
#endif /* _LINUX_BPF_H */
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -738,12 +738,14 @@ static int try_get_fmt_tmp_buf(char **tm
return 0;
}
-void bpf_bprintf_cleanup(void)
+void bpf_bprintf_cleanup(struct bpf_bprintf_data *data)
{
- if (this_cpu_read(bpf_bprintf_nest_level)) {
- this_cpu_dec(bpf_bprintf_nest_level);
- preempt_enable();
- }
+ if (!data->bin_args)
+ return;
+ if (WARN_ON_ONCE(this_cpu_read(bpf_bprintf_nest_level) == 0))
+ return;
+ this_cpu_dec(bpf_bprintf_nest_level);
+ preempt_enable();
}
/*
@@ -975,7 +977,7 @@ nocopy_fmt:
err = 0;
out:
if (err)
- bpf_bprintf_cleanup();
+ bpf_bprintf_cleanup(data);
return err;
}
@@ -1001,7 +1003,7 @@ BPF_CALL_5(bpf_snprintf, char *, str, u3
err = bstr_printf(str, str_size, fmt, data.bin_args);
- bpf_bprintf_cleanup();
+ bpf_bprintf_cleanup(&data);
return err + 1;
}
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -387,7 +387,7 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt
trace_bpf_trace_printk(buf);
raw_spin_unlock_irqrestore(&trace_printk_lock, flags);
- bpf_bprintf_cleanup();
+ bpf_bprintf_cleanup(&data);
return ret;
}
@@ -435,7 +435,7 @@ BPF_CALL_5(bpf_seq_printf, struct seq_fi
seq_bprintf(m, fmt, data.bin_args);
- bpf_bprintf_cleanup();
+ bpf_bprintf_cleanup(&data);
return seq_has_overflowed(m) ? -EOVERFLOW : 0;
}
Patches currently in stable-queue which might be from kroah.com@xxxxxxxxxxxxxxx are
queue-5.15/bpf-add-struct-for-bin_args-arg-in-bpf_bprintf_prepare.patch
queue-5.15/bpf-do-cleanup-in-bpf_bprintf_cleanup-only-when-needed.patch
queue-5.15/bpf-merge-printk-and-seq_printf-vararg-max-macros.patch
queue-5.15/smb-client-fix-potential-oobs-in-smb2_parse_contexts.patch
queue-5.15/bpf-remove-trace_printk_lock.patch
queue-5.15/smb-client-fix-parsing-of-smb3.1.1-posix-create-context.patch
queue-5.15/smb-client-fix-oob-in-receive_encrypted_standard.patch
