From: Zheng Yejian zhengyejian1@huawei.com
mainline inclusion from mainline-v6.5-rc2 commit 26efd79c4624294e553aeaa3439c646729bad084 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I7KYPM CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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As comments in ftrace_process_locs(), there may be NULL pointers in mcount_loc section:
Some architecture linkers will pad between the different mcount_loc sections of different object files to satisfy alignments. Skip any NULL pointers.
After commit 20e5227e9f55 ("ftrace: allow NULL pointers in mcount_loc"), NULL pointers will be accounted when allocating ftrace pages but skipped before adding into ftrace pages, this may result in some pages not being used. Then after commit 706c81f87f84 ("ftrace: Remove extra helper functions"), warning may occur at: WARN_ON(pg->next);
To fix it, only warn for case that no pointers skipped but pages not used up, then free those unused pages after releasing ftrace_lock.
Link: https://lore.kernel.org/linux-trace-kernel/20230712060452.3175675-1-zhengyej...
Cc: stable@vger.kernel.org Fixes: 706c81f87f84 ("ftrace: Remove extra helper functions") Suggested-by: Steven Rostedt rostedt@goodmis.org Signed-off-by: Zheng Yejian zhengyejian1@huawei.com Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Reviewed-by: Xu Kuohai xukuohai@huawei.com Signed-off-by: Yongqiang Liu liuyongqiang13@huawei.com --- kernel/trace/ftrace.c | 41 +++++++++++++++++++++++++++++------------ 1 file changed, 29 insertions(+), 12 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index e6aa32a27149..3ea4c9fa8b57 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -3048,12 +3048,25 @@ static int ftrace_allocate_records(struct ftrace_page *pg, int count) return cnt; }
+static void ftrace_free_pages(struct ftrace_page *pages) +{ + struct ftrace_page *pg = pages; + int order; + + while (pg) { + order = get_count_order(pg->size / ENTRIES_PER_PAGE); + free_pages((unsigned long)pg->records, order); + pages = pg->next; + kfree(pg); + pg = pages; + } +} + static struct ftrace_page * ftrace_allocate_pages(unsigned long num_to_init) { struct ftrace_page *start_pg; struct ftrace_page *pg; - int order; int cnt;
if (!num_to_init) @@ -3087,14 +3100,7 @@ ftrace_allocate_pages(unsigned long num_to_init) return start_pg;
free_pages: - pg = start_pg; - while (pg) { - order = get_count_order(pg->size / ENTRIES_PER_PAGE); - free_pages((unsigned long)pg->records, order); - start_pg = pg->next; - kfree(pg); - pg = start_pg; - } + ftrace_free_pages(start_pg); pr_info("ftrace: FAILED to allocate memory for functions\n"); return NULL; } @@ -5575,9 +5581,11 @@ static int ftrace_process_locs(struct module *mod, unsigned long *start, unsigned long *end) { + struct ftrace_page *pg_unuse = NULL; struct ftrace_page *start_pg; struct ftrace_page *pg; struct dyn_ftrace *rec; + unsigned long skipped = 0; unsigned long count; unsigned long *p; unsigned long addr; @@ -5630,8 +5638,10 @@ static int ftrace_process_locs(struct module *mod, * object files to satisfy alignments. * Skip any NULL pointers. */ - if (!addr) + if (!addr) { + skipped++; continue; + }
if (pg->index == pg->size) { /* We should have allocated enough */ @@ -5644,8 +5654,10 @@ static int ftrace_process_locs(struct module *mod, rec->ip = addr; }
- /* We should have used all pages */ - WARN_ON(pg->next); + if (pg->next) { + pg_unuse = pg->next; + pg->next = NULL; + }
/* Assign the last page to ftrace_pages */ ftrace_pages = pg; @@ -5667,6 +5679,11 @@ static int ftrace_process_locs(struct module *mod, out: mutex_unlock(&ftrace_lock);
+ /* We should have used all pages unless we skipped some */ + if (pg_unuse) { + WARN_ON(!skipped); + ftrace_free_pages(pg_unuse); + } return ret; }