From: Tze-nan Wu Tze-nan.Wu@mediatek.com

stable inclusion from stable-v4.19.320 commit 302ceb625d7b990db205a15e371f9a71238de91c category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAMMUB CVE: CVE-2024-43890

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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commit bcf86c01ca4676316557dd482c8416ece8c2e143 upstream.

"tracing_map->next_elt" in get_free_elt() is at risk of overflowing.

Once it overflows, new elements can still be inserted into the tracing_map even though the maximum number of elements (`max_elts`) has been reached. Continuing to insert elements after the overflow could result in the tracing_map containing "tracing_map->max_size" elements, leaving no empty entries. If any attempt is made to insert an element into a full tracing_map using `__tracing_map_insert()`, it will cause an infinite loop with preemption disabled, leading to a CPU hang problem.

Fix this by preventing any further increments to "tracing_map->next_elt" once it reaches "tracing_map->max_elt".

Cc: stable@vger.kernel.org Cc: Masami Hiramatsu mhiramat@kernel.org Fixes: 08d43a5fa063e ("tracing: Add lock-free tracing_map") Co-developed-by: Cheng-Jui Wang cheng-jui.wang@mediatek.com Link: https://lore.kernel.org/20240805055922.6277-1-Tze-nan.Wu@mediatek.com Signed-off-by: Cheng-Jui Wang cheng-jui.wang@mediatek.com Signed-off-by: Tze-nan Wu Tze-nan.Wu@mediatek.com Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Liu Chuang liuchuang40@huawei.com --- kernel/trace/tracing_map.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/tracing_map.c b/kernel/trace/tracing_map.c index da7337f0c9bc..5e534ef6d695 100644 --- a/kernel/trace/tracing_map.c +++ b/kernel/trace/tracing_map.c @@ -451,7 +451,7 @@ static struct tracing_map_elt *get_free_elt(struct tracing_map *map) struct tracing_map_elt *elt = NULL; int idx;

- idx = atomic_inc_return(&map->next_elt); + idx = atomic_fetch_add_unless(&map->next_elt, 1, map->max_elts); if (idx < map->max_elts) { elt = *(TRACING_MAP_ELT(map->elts, idx)); if (map->ops && map->ops->elt_init) @@ -696,7 +696,7 @@ void tracing_map_clear(struct tracing_map *map) { unsigned int i;

- atomic_set(&map->next_elt, -1); + atomic_set(&map->next_elt, 0); atomic64_set(&map->hits, 0); atomic64_set(&map->drops, 0);

@@ -780,7 +780,7 @@ struct tracing_map *tracing_map_create(unsigned int map_bits,

map->map_bits = map_bits; map->max_elts = (1 << map_bits); - atomic_set(&map->next_elt, -1); + atomic_set(&map->next_elt, 0);

map->map_size = (1 << (map_bits + 1)); map->ops = ops;