The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x c4d6b5438116c184027b2e911c0f2c7c406fb47c # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023082711-crown-acuteness-453a@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

c4d6b5438116 ("tracing/synthetic: Allocate one additional element for size") fc1a9dc10129 ("tracing/histogram: Don't use strlen to find length of stacktrace variables") 288709c9f3b0 ("tracing: Allow stacktraces to be saved as histogram variables") 5f2e094ed259 ("tracing: Allow multiple hitcount values in histograms") 0934ae9977c2 ("tracing: Fix reading strings from synthetic events") 86087383ec0a ("tracing/hist: Call hist functions directly via a switch statement") 05770dd0ad11 ("tracing: Support __rel_loc relative dynamic data location attribute") 938aa33f1465 ("tracing: Add length protection to histogram string copies") 63f84ae6b82b ("tracing/histogram: Do not copy the fixed-size char array field over the field size") 8b5d46fd7a38 ("tracing/histogram: Optimize division by constants") f47716b7a955 ("tracing/histogram: Covert expr to const if both operands are constants") c5eac6ee8bc5 ("tracing/histogram: Simplify handling of .sym-offset in expressions") 9710b2f341a0 ("tracing: Fix operator precedence for hist triggers expression") bcef04415032 ("tracing: Add division and multiplication support for hist triggers") 52cfb373536a ("tracing: Add support for creating hist trigger variables from literal")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From c4d6b5438116c184027b2e911c0f2c7c406fb47c Mon Sep 17 00:00:00 2001 From: Sven Schnelle svens@linux.ibm.com Date: Wed, 16 Aug 2023 17:49:28 +0200 Subject: [PATCH] tracing/synthetic: Allocate one additional element for size

While debugging another issue I noticed that the stack trace contains one invalid entry at the end:

<idle>-0 [008] d..4. 26.484201: wake_lat: pid=0 delta=2629976084 000000009cc24024 stack=STACK: => __schedule+0xac6/0x1a98 => schedule+0x126/0x2c0 => schedule_timeout+0x150/0x2c0 => kcompactd+0x9ca/0xc20 => kthread+0x2f6/0x3d8 => __ret_from_fork+0x8a/0xe8 => 0x6b6b6b6b6b6b6b6b

This is because the code failed to add the one element containing the number of entries to field_size.

Link: https://lkml.kernel.org/r/20230816154928.4171614-4-svens@linux.ibm.com

Cc: Masami Hiramatsu mhiramat@kernel.org Fixes: 00cf3d672a9d ("tracing: Allow synthetic events to pass around stacktraces") Signed-off-by: Sven Schnelle svens@linux.ibm.com Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org

diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c index 80a2a832f857..9897d0bfcab7 100644 --- a/kernel/trace/trace_events_synth.c +++ b/kernel/trace/trace_events_synth.c @@ -528,7 +528,8 @@ static notrace void trace_event_raw_event_synth(void *__data, str_val = (char *)(long)var_ref_vals[val_idx];

if (event->dynamic_fields[i]->is_stack) { - len = *((unsigned long *)str_val); + /* reserve one extra element for size */ + len = *((unsigned long *)str_val) + 1; len *= sizeof(unsigned long); } else { len = fetch_store_strlen((unsigned long)str_val);