From 5e6ded2e7a5d9c71186acc8f51989ef6e6addda4 Mon Sep 17 00:00:00 2001 From: Tom Rix Date: Sat, 19 Mar 2022 18:51:43 -0700 Subject: [PATCH] livepatch: Reorder to use before freeing a pointer Clang static analysis reports this issue livepatch-shadow-fix1.c:113:2: warning: Use of memory after it is freed pr_info("%s: dummy @ %p, prevented leak @ %p\n", ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The pointer is freed in the previous statement. Reorder the pr_info to report before the free. Similar issue in livepatch-shadow-fix2.c Note that it is a false positive. pr_info() just prints the address. The freed memory is not accessed. Well, the static analyzer could not know this easily. Signed-off-by: Tom Rix Reviewed-by: Petr Mladek Acked-by: David Vernet Acked-by: Joe Lawrence [pmladek@suse.com: Note about that it was false positive.] Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20220320015143.2208591-1-trix@redhat.com --- samples/livepatch/livepatch-shadow-fix1.c | 2 +- samples/livepatch/livepatch-shadow-fix2.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/samples/livepatch/livepatch-shadow-fix1.c b/samples/livepatch/livepatch-shadow-fix1.c index 918ce17b43fd..6701641bf12d 100644 --- a/samples/livepatch/livepatch-shadow-fix1.c +++ b/samples/livepatch/livepatch-shadow-fix1.c @@ -109,9 +109,9 @@ static void livepatch_fix1_dummy_leak_dtor(void *obj, void *shadow_data) void *d = obj; int **shadow_leak = shadow_data; - kfree(*shadow_leak); pr_info("%s: dummy @ %p, prevented leak @ %p\n", __func__, d, *shadow_leak); + kfree(*shadow_leak); } static void livepatch_fix1_dummy_free(struct dummy *d) diff --git a/samples/livepatch/livepatch-shadow-fix2.c b/samples/livepatch/livepatch-shadow-fix2.c index 29fe5cd42047..361046a4f10c 100644 --- a/samples/livepatch/livepatch-shadow-fix2.c +++ b/samples/livepatch/livepatch-shadow-fix2.c @@ -61,9 +61,9 @@ static void livepatch_fix2_dummy_leak_dtor(void *obj, void *shadow_data) void *d = obj; int **shadow_leak = shadow_data; - kfree(*shadow_leak); pr_info("%s: dummy @ %p, prevented leak @ %p\n", __func__, d, *shadow_leak); + kfree(*shadow_leak); } static void livepatch_fix2_dummy_free(struct dummy *d) -- 2.11.0