linux-stable.git/kernel/trace/trace_probe.c, branch v6.18.42

tracing/probes: Prevent out-of-bounds write in __trace_probe_log_err()

2026-08-03T09:22:00+00:00

commit a9d6fb284039a5d3858a1d9f9a0d7e46cfb7c2d4 upstream.

If trace_probe_log.argc is 0 in __trace_probe_log_err(), the loop
constructing the command string will not execute and p will remain equal to
command. Writing to *(p - 1) will cause an out-of-bounds access before
command. This should not happen, but better to be treated.

Reject if trace_probe_log.argc is 0.

Link: https://lore.kernel.org/all/178454233992.290363.18323091580600697731.stgit@devnote2/

Fixes: ab105a4fb894 ("tracing: Use tracing error_log with probe events")
Cc: stable@vger.kernel.org
Assisted-by: Antigravity:gemini-3.5-flash
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

tracing/probes: Fix potential underflow in LEN_OR_ZERO macro

2026-08-03T09:22:00+00:00

commit 8ce20bfba48902e1382187cd1a852f7cf3a1e739 upstream.

In __set_print_fmt(), LEN_OR_ZERO is defined as (len ? len - pos : 0).
If len is non-zero but smaller than pos, len - pos evaluates to a negative
integer. When passed as a size argument to snprintf(), this negative value
is cast to a large unsigned size_t, bypassing buffer size limits.

Ensure len > pos before subtracting to avoid integer underflow.

Link: https://lore.kernel.org/all/178454234934.290363.15247317871499514139.stgit@devnote2/

Fixes: 5bf652aaf46c ("tracing/probes: Integrate duplicate set_print_fmt()")
Cc: stable@vger.kernel.org
Assisted-by: Antigravity:gemini-3.5-flash
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

tracing/probes: Avoid temporary buffer truncation in trace_probe_match_command_args()

2026-08-03T09:22:00+00:00

commit 15f197856d68882af9416fc97516bb55079b7677 upstream.

In trace_probe_match_command_args(), a stack buffer buf[MAX_ARGSTR_LEN + 1]
(256 bytes) is used to format "=". However, since name can
be up to 32 bytes (MAX_ARG_NAME_LEN) and comm up to 255 bytes
(MAX_ARGSTR_LEN), the formatted string can exceed 256 bytes and get
truncated by snprintf(), causing spurious argument matching failures.

Instead of formatting into a temporary buffer on stack, compare the
argument name, the '=' delimiter, and the comm expression directly.

Link: https://lore.kernel.org/all/178454233010.290363.10428767141343428804.stgit@devnote2/

Fixes: eb5bf81330a7 ("tracing/kprobe: Add per-probe delete from event")
Cc: stable@vger.kernel.org
Assisted-by: Antigravity:gemini-3.5-flash
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

tracing/probes: Fix double addition of offset for @+FOFFSET

2026-07-24T14:17:14+00:00

commit 9a667b7750dda88cbf1cca96a53a2163b2ee71f7 upstream.

Since commit 533059281ee5 ("tracing: probeevent: Introduce new argument
 fetching code") wrongly use @offset local variable during the parsing,
the offset value is added twice when dereferencing.
Reset the @offset after setting it in FETCH_OP_FOFFS.

Link: https://lore.kernel.org/all/178217905962.643090.1978577464942171332.stgit@devnote2/

Fixes: 533059281ee5 ("tracing: probeevent: Introduce new argument fetching code")
Signed-off-by: Masami Hiramatsu (Google) 
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman

tracing/probes: Make the $ prefix mandatory for comm access

2026-07-24T14:16:43+00:00

[ Upstream commit a369299c3f785cf556bbef2de2db0aa2d294c4c9 ]

Since $comm or $COMM are not event field but special fetcharg
variables to access current->comm, It should not be accessed
without '$' prefix even with typecast.

Link: https://lore.kernel.org/all/178231209724.732967.12049805699091810641.stgit@devnote2/

Fixes: 69efd863a785 ("tracing/eprobes: Allow use of BTF names to dereference pointers")
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Sasha Levin

tracing/probes: Remove WARN_ON_ONCE from parse_btf_arg

2026-07-24T14:16:42+00:00

[ Upstream commit 251a8fe1b9aedccd298b77bc28426d564c5a923f ]

Sashiko found that user can cause this WARN_ON_ONCE() easily
with adding a kprobe event based on a raw address with BTF
parameter.

Since this is not an unexpected condition, remove the
WARN_ON_ONCE().

Link: https://lore.kernel.org/all/178177265367.2059927.13789953014706792126.stgit@mhiramat.tok.corp.google.com/

Link: https://sashiko.dev/#/patchset/178165816303.269421.7302603996990753309.stgit%40devnote2

Reported-by: Sashiko 
Fixes: b576e09701c7 ("tracing/probes: Support function parameters if BTF is available")
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Sasha Levin

tracing/eprobes: Allow use of BTF names to dereference pointers

2026-07-24T14:16:42+00:00

[ Upstream commit 69efd863a78584b9416ed6be0e1e7349124b4a00 ]

Add syntax to the parsing of eprobes to be able to typecast a trace event
field that is a pointer to a structure.

Currently, a dereference must be a number, where the user has to figure
out manually the offset of a member of a structure that they want to
dereference.

But for event probes that records a field that happens to be a pointer to
a structure, it cannot dereference these values with BTF naming, but
must use numerical offsets.

For example, to find out what device a sk_buff is pointing to in the
net_dev_xmit trace event, one must first use gdb to find the offsets of the
members of the structures:

 (gdb) p &((struct sk_buff *)0)->dev
 $1 = (struct net_device **) 0x10
 (gdb) p &((struct net_device *)0)->name
 $2 = (char (*)[16]) 0x118

And then use the raw numbers to dereference:

  # echo 'e:xmit net.net_dev_xmit +0x118(+0x10($skbaddr)):string' >> dynamic_events

If BTF is in the kernel, then instead, the skbaddr can be typecast to
sk_buff and use the normal dereference logic.

  # echo 'e:xmit net.net_dev_xmit (sk_buff)skbaddr->dev->name:string' >> dynamic_events
  # echo 1 > events/eprobes/xmit/enable
  # cat trace
[..]
    sshd-session-1022    [000] b..2.   860.249343: xmit: (net.net_dev_xmit) arg1="enp7s0"
    sshd-session-1022    [000] b..2.   860.250061: xmit: (net.net_dev_xmit) arg1="enp7s0"
    sshd-session-1022    [000] b..2.   860.250142: xmit: (net.net_dev_xmit) arg1="enp7s0"
    sshd-session-1022    [000] b..2.   860.263553: xmit: (net.net_dev_xmit) arg1="enp7s0"
    sshd-session-1022    [000] b..2.   860.283820: xmit: (net.net_dev_xmit) arg1="enp7s0"
    sshd-session-1022    [000] b..2.   860.302716: xmit: (net.net_dev_xmit) arg1="enp7s0"
    sshd-session-1022    [000] b..2.   860.322905: xmit: (net.net_dev_xmit) arg1="enp7s0"
    sshd-session-1022    [000] b..2.   860.342828: xmit: (net.net_dev_xmit) arg1="enp7s0"
    sshd-session-1022    [000] b..2.   860.362268: xmit: (net.net_dev_xmit) arg1="enp7s0"
    sshd-session-1022    [000] b..2.   860.382335: xmit: (net.net_dev_xmit) arg1="enp7s0"
    sshd-session-1022    [000] b..2.   860.400856: xmit: (net.net_dev_xmit) arg1="enp7s0"
    sshd-session-1022    [000] b..2.   860.419893: xmit: (net.net_dev_xmit) arg1="enp7s0"

The syntax is simply: (STRUCT)(FIELD)->MEMBER[->MEMBER..]

Also add comments around the #else and #endif of #ifdef CONFIG_PROBE_EVENTS_BTF_ARGS
to know what they are for.

Link: https://lore.kernel.org/all/20260601130746.2139d926@gandalf.local.home/

Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Masami Hiramatsu (Google) 
Stable-dep-of: 251a8fe1b9ae ("tracing/probes: Remove WARN_ON_ONCE from parse_btf_arg")
Signed-off-by: Sasha Levin

tracing/probes: Point the error offset correctly for eprobe argument error

2026-06-19T11:44:03+00:00

commit 85e0f27dd1396307913ffc5745b0c05137e9beac upstream.

Fix to point the error offset correctly for eprobe argument error.
In the cleanup commit 1b8b0cd754cd ("tracing/probes: Move event parameter
fetching code to common parser"), due to incorrect backward compatibility
aimed at conforming to the test specifications, the error location was set
to 0 when a non-existent formal parameter was specified for Eprobe.
However, this should be corrected in both the test and the implementation
to point correct error position.

Link: https://lore.kernel.org/all/177967567399.209006.1451571244515632097.stgit@devnote2/

Fixes: 1b8b0cd754cd ("tracing/probes: Move event parameter fetching code to common parser")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) 
Reviewed-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

tracing/probes: Limit size of event probe to 3K

2026-05-14T13:30:18+00:00

commit b2aa3b4d64e460ac606f386c24e7d8a873ce6f1a upstream.

There currently isn't a max limit an event probe can be. One could make an
event greater than PAGE_SIZE, which makes the event useless because if
it's bigger than the max event that can be recorded into the ring buffer,
then it will never be recorded.

A event probe should never need to be greater than 3K, so make that the
max size. As long as the max is less than the max that can be recorded
onto the ring buffer, it should be fine.

Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers 
Acked-by: Masami Hiramatsu (Google) 
Fixes: 93ccae7a22274 ("tracing/kprobes: Support basic types on dynamic events")
Link: https://patch.msgid.link/20260428122302.706610ba@gandalf.local.home
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

tracing/probe: reject non-closed empty immediate strings

2026-04-22T11:22:20+00:00

[ Upstream commit 4346be6577aaa04586167402ae87bbdbe32484a4 ]

parse_probe_arg() accepts quoted immediate strings and passes the body
after the opening quote to __parse_imm_string(). That helper currently
computes strlen(str) and immediately dereferences str[len - 1], which
underflows when the body is empty and not closed with double-quotation.

Reject empty non-closed immediate strings before checking for the closing quote.

Link: https://lore.kernel.org/all/20260401160315.88518-1-pengpeng@iscas.ac.cn/

Fixes: a42e3c4de964 ("tracing/probe: Add immediate string parameter support")
Signed-off-by: Pengpeng Hou 
Reviewed-by: Steven Rostedt (Google) 
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Sasha Levin