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| author | Tze-nan Wu <Tze-nan.Wu@mediatek.com> | 2024-08-05 13:59:22 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-08-19 05:33:53 +0200 |
| commit | d3e4dbc2858fe85d1dbd2e72a9fc5dea988b5c18 (patch) | |
| tree | 943f99af25eef875ebbded0de96be677018f7d63 /kernel | |
| parent | f8fe71c64923f2dfe18a8968f32168a20277be00 (diff) | |
| download | linux-d3e4dbc2858fe85d1dbd2e72a9fc5dea988b5c18.tar.gz linux-d3e4dbc2858fe85d1dbd2e72a9fc5dea988b5c18.tar.bz2 linux-d3e4dbc2858fe85d1dbd2e72a9fc5dea988b5c18.zip | |
tracing: Fix overflow in get_free_elt()
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>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/tracing_map.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/trace/tracing_map.c b/kernel/trace/tracing_map.c index 33c463967bb3..208cfe24c547 100644 --- a/kernel/trace/tracing_map.c +++ b/kernel/trace/tracing_map.c @@ -454,7 +454,7 @@ 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) @@ -699,7 +699,7 @@ 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); @@ -783,7 +783,7 @@ 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; |