Patch "ftrace: Check if pages were allocated before calling free_pages()" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    ftrace: Check if pages were allocated before calling free_pages()

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ftrace-check-if-pages-were-allocated-before-calling-.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 82d0c3cbc9c2961a91d2463724758e7895fd11ff
Author: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Date:   Tue Mar 30 09:58:38 2021 -0400

    ftrace: Check if pages were allocated before calling free_pages()
    
    [ Upstream commit 59300b36f85f254260c81d9dd09195fa49eb0f98 ]
    
    It is possible that on error pg->size can be zero when getting its order,
    which would return a -1 value. It is dangerous to pass in an order of -1
    to free_pages(). Check if order is greater than or equal to zero before
    calling free_pages().
    
    Link: https://lore.kernel.org/lkml/20210330093916.432697c7@xxxxxxxxxxxxxxxxxx/
    
    Reported-by: Abaci Robot <abaci@xxxxxxxxxxxxxxxxx>
    Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
    Stable-dep-of: 26efd79c4624 ("ftrace: Fix possible warning on checking all pages used in ftrace_process_locs()")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 48ab4d750c650..1b92a22086f50 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3095,7 +3095,8 @@ ftrace_allocate_pages(unsigned long num_to_init)
 	pg = start_pg;
 	while (pg) {
 		order = get_count_order(pg->size / ENTRIES_PER_PAGE);
-		free_pages((unsigned long)pg->records, order);
+		if (order >= 0)
+			free_pages((unsigned long)pg->records, order);
 		start_pg = pg->next;
 		kfree(pg);
 		pg = start_pg;
@@ -5843,7 +5844,8 @@ void ftrace_release_mod(struct module *mod)
 		clear_mod_from_hashes(pg);
 
 		order = get_count_order(pg->size / ENTRIES_PER_PAGE);
-		free_pages((unsigned long)pg->records, order);
+		if (order >= 0)
+			free_pages((unsigned long)pg->records, order);
 		tmp_page = pg->next;
 		kfree(pg);
 		ftrace_number_of_pages -= 1 << order;
@@ -6192,7 +6194,8 @@ void ftrace_free_mem(struct module *mod, void *start_ptr, void *end_ptr)
 		if (!pg->index) {
 			*last_pg = pg->next;
 			order = get_count_order(pg->size / ENTRIES_PER_PAGE);
-			free_pages((unsigned long)pg->records, order);
+			if (order >= 0)
+				free_pages((unsigned long)pg->records, order);
 			ftrace_number_of_pages -= 1 << order;
 			ftrace_number_of_groups--;
 			kfree(pg);