From 98495b5a4d77dd22e106f462b76e1093a55b29a7 Mon Sep 17 00:00:00 2001 From: Junrui Luo Date: Thu, 4 Jun 2026 15:34:25 +0800 Subject: [PATCH] coresight: ultrasoc-smb: Fix OOB write in smb_sync_perf_buffer() When the SMB sink is used as a perf AUX sink, smb_update_buffer() calls smb_sync_perf_buffer() to copy hardware trace data into the perf AUX ring buffer pages. It derives pg_idx = head >> PAGE_SHIFT from @head, which is handle->head, and indexes dst_pages[pg_idx]. The pg_idx %= nr_pages normalization is only applied after the first loop iteration. This leaves the initial page index underived from the buffer size, which can result in an out-of-bounds write past dst_pages[] when head exceeds the AUX buffer size. Normalize head modulo the AUX buffer size before deriving the page index and offset, mirroring tmc_etr_sync_perf_buffer(). Fixes: 06f5c2926aaa ("drivers/coresight: Add UltraSoc System Memory Buffer driver") Reported-by: Yuhao Jiang Cc: stable@vger.kernel.org Signed-off-by: Junrui Luo Signed-off-by: Suzuki K Poulose Link: https://lore.kernel.org/r/SYBPR01MB788156B3380A36835DB22290AF102@SYBPR01MB7881.ausprd01.prod.outlook.com --- drivers/hwtracing/coresight/ultrasoc-smb.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/hwtracing/coresight/ultrasoc-smb.c b/drivers/hwtracing/coresight/ultrasoc-smb.c index 5776f63468fa..20a950b9dd4f 100644 --- a/drivers/hwtracing/coresight/ultrasoc-smb.c +++ b/drivers/hwtracing/coresight/ultrasoc-smb.c @@ -337,6 +337,7 @@ static void smb_sync_perf_buffer(struct smb_drv_data *drvdata, unsigned long to_copy; long pg_idx, pg_offset; + head %= (unsigned long)buf->nr_pages << PAGE_SHIFT; pg_idx = head >> PAGE_SHIFT; pg_offset = head & (PAGE_SIZE - 1);