From: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>
To: rostedt@goodmis.org
Cc: linux-trace-devel@vger.kernel.org
Subject: [PATCH] trace-cmd: Fix segmentation fault in tracecmd_read_at() in specific use case
Date: Fri, 11 Oct 2019 14:33:53 +0300 [thread overview]
Message-ID: <20191011113353.11652-1-tz.stoyanov@gmail.com> (raw)
There is a segmentation fault in update_page_info() when the requested page
is not loaded, handle->cpu_data[cpu].page is NULL. The problematic flow starts
from tracecmd_read_at() API, when reading offset in the first page (less than 4K),
and this page is still not loaded yet. The problem can be observed randomly -
there is a sporadic KernelShark crash when loading a file, browsing and
zooming events.
https://bugzilla.kernel.org/show_bug.cgi?id=205165
Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
lib/trace-cmd/trace-input.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index 6102eb3..da77418 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -1278,7 +1278,8 @@ tracecmd_read_at(struct tracecmd_input *handle, unsigned long long offset,
/* check to see if we have this page already */
for (cpu = 0; cpu < handle->cpus; cpu++) {
if (handle->cpu_data[cpu].offset == page_offset &&
- handle->cpu_data[cpu].file_size)
+ handle->cpu_data[cpu].file_size &&
+ handle->cpu_data[cpu].page)
break;
}
--
2.21.0
next reply other threads:[~2019-10-11 11:33 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-11 11:33 Tzvetomir Stoyanov (VMware) [this message]
2019-10-14 14:07 ` [PATCH] trace-cmd: Fix segmentation fault in tracecmd_read_at() in specific use case Steven Rostedt
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191011113353.11652-1-tz.stoyanov@gmail.com \
--to=tz.stoyanov@gmail.com \
--cc=linux-trace-devel@vger.kernel.org \
--cc=rostedt@goodmis.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).