From 185b29c6151cf3a5c387ca5904c51c6af3292a0c Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Fri, 6 May 2022 09:55:15 +0300 Subject: [PATCH] test_firmware: fix end of loop test in upload_read_show() If a list_for_each_entry() loop exits without hitting a break statement then the iterator points to invalid memory. So in this code the "tst->name" dereference is an out bounds read. It's an offset from the &test_upload_list pointer and it will likely work fine most of the time but it's not correct. One alternative is to fix this this by changing the test to: if (list_entry_is_head(tst, &test_upload_list, node)) { But the simpler, trendy new way is just create a new variable and test for NULL. Fixes: a31ad463b72d ("test_firmware: Add test support for firmware upload") Reviewed-by: Russ Weight Acked-by: Luis Chamberlain Signed-off-by: Dan Carpenter Link: https://lore.kernel.org/r/YnTGU3UJOIA09I7e@kili Signed-off-by: Greg Kroah-Hartman --- lib/test_firmware.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/lib/test_firmware.c b/lib/test_firmware.c index 76115c1a2629..c82b65947ce6 100644 --- a/lib/test_firmware.c +++ b/lib/test_firmware.c @@ -1392,7 +1392,8 @@ static ssize_t upload_read_show(struct device *dev, struct device_attribute *attr, char *buf) { - struct test_firmware_upload *tst; + struct test_firmware_upload *tst = NULL; + struct test_firmware_upload *tst_iter; int ret = -EINVAL; if (!test_fw_config->upload_name) { @@ -1401,11 +1402,13 @@ static ssize_t upload_read_show(struct device *dev, } mutex_lock(&test_fw_mutex); - list_for_each_entry(tst, &test_upload_list, node) - if (tst->name == test_fw_config->upload_name) + list_for_each_entry(tst_iter, &test_upload_list, node) + if (tst_iter->name == test_fw_config->upload_name) { + tst = tst_iter; break; + } - if (tst->name != test_fw_config->upload_name) { + if (!tst) { pr_err("Firmware name not found: %s\n", test_fw_config->upload_name); goto out;