From f32dacc8255131c8e9bcaac9066b0809fdf7115c Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?kiyin=28=E5=B0=B9=E4=BA=AE=29?= Date: Mon, 16 Nov 2020 14:58:19 +0800 Subject: [PATCH] perf/core: Fix a memory leak in perf_event_parse_addr_filter() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit mainline inclusion from mainline-v5.10-rc3 commit 7bdb157cdebbf95a1cd94ed2e01b338714075d00 category: bugfix bugzilla: NA CVE: CVE-2020-25704 -------------------------------- As shown through runtime testing, the "filename" allocation is not always freed in perf_event_parse_addr_filter(). There are three possible ways that this could happen: - It could be allocated twice on subsequent iterations through the loop, - or leaked on the success path, - or on the failure path. Clean up the code flow to make it obvious that 'filename' is always freed in the reallocation path and in the two return paths as well. We rely on the fact that kfree(NULL) is NOP and filename is initialized with NULL. This fixes the leak. No other side effects expected. [ Dan Carpenter: cleaned up the code flow & added a changelog. ] [ Ingo Molnar: updated the changelog some more. ] Fixes: 375637bc5249 ("perf/core: Introduce address range filtering") Signed-off-by: "kiyin(尹亮)" Signed-off-by: Dan Carpenter Signed-off-by: Ingo Molnar Cc: "Srivatsa S. Bhat" Cc: Anthony Liguori Reviewed-by: Jian Cheng Reviewed-by: Jason Yan Signed-off-by: Yang Yingliang --- kernel/events/core.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 452775f68129..d65ad6afdcda 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9069,6 +9069,7 @@ perf_event_parse_addr_filter(struct perf_event *event, char *fstr, if (token == IF_SRC_FILE || token == IF_SRC_FILEADDR) { int fpos = token == IF_SRC_FILE ? 2 : 1; + kfree(filename); filename = match_strdup(&args[fpos]); if (!filename) { ret = -ENOMEM; @@ -9115,16 +9116,13 @@ perf_event_parse_addr_filter(struct perf_event *event, char *fstr, */ ret = -EOPNOTSUPP; if (!event->ctx->task) - goto fail_free_name; + goto fail; /* look up the path and grab its inode */ ret = kern_path(filename, LOOKUP_FOLLOW, &filter->path); if (ret) - goto fail_free_name; - - kfree(filename); - filename = NULL; + goto fail; ret = -EINVAL; if (!filter->path.dentry || @@ -9144,13 +9142,13 @@ perf_event_parse_addr_filter(struct perf_event *event, char *fstr, if (state != IF_STATE_ACTION) goto fail; + kfree(filename); kfree(orig); return 0; -fail_free_name: - kfree(filename); fail: + kfree(filename); free_filters_list(filters); kfree(orig); -- GitLab