On Wed, Nov 26, 2025 at 09:38:30PM +0530, Ankit Khushwaha wrote: > In "uffd-stress.c" & "uffd-unit-tests.c". address of char variable having > garbage value (uninitialized) is passed to 'write' syscall triggers > warning. > > uffd-stress.c:246:39: warning: variable 'c' is uninitialized when > passed as a const pointer argument here > [-Wuninitialized-const-pointer] > > uffd-unit-tests.c:581:31: warning: variable 'c' is uninitialized > when passed as a const pointer argument here > [-Wuninitialized-const-pointer] > > so the fix is to assign char variable to '\0' to prevent writing of > garbage value. > > Signed-off-by: Ankit Khushwaha <[email protected]>
Reviewed-by: Mike Rapoport (Microsoft) <[email protected]> > --- > this warning is raised with clang version 21.1.5 (Fedora 21.1.5-1.fc43). > --- > tools/testing/selftests/mm/uffd-stress.c | 2 +- > tools/testing/selftests/mm/uffd-unit-tests.c | 8 ++++---- > 2 files changed, 5 insertions(+), 5 deletions(-) > > diff --git a/tools/testing/selftests/mm/uffd-stress.c > b/tools/testing/selftests/mm/uffd-stress.c > index b51c89e1cd1a..700fbaa18d44 100644 > --- a/tools/testing/selftests/mm/uffd-stress.c > +++ b/tools/testing/selftests/mm/uffd-stress.c > @@ -241,7 +241,7 @@ static int stress(struct uffd_args *args) > return 1; > > for (cpu = 0; cpu < gopts->nr_parallel; cpu++) { > - char c; > + char c = '\0'; > if (bounces & BOUNCE_POLL) { > if (write(gopts->pipefd[cpu*2+1], &c, 1) != 1) > err("pipefd write error"); > diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c > b/tools/testing/selftests/mm/uffd-unit-tests.c > index f917b4c4c943..f4807242c5b2 100644 > --- a/tools/testing/selftests/mm/uffd-unit-tests.c > +++ b/tools/testing/selftests/mm/uffd-unit-tests.c > @@ -543,7 +543,7 @@ static void > uffd_minor_test_common(uffd_global_test_opts_t *gopts, bool test_col > { > unsigned long p; > pthread_t uffd_mon; > - char c; > + char c = '\0'; > struct uffd_args args = { 0 }; > args.gopts = gopts; > > @@ -759,7 +759,7 @@ static void > uffd_sigbus_test_common(uffd_global_test_opts_t *gopts, bool wp) > pthread_t uffd_mon; > pid_t pid; > int err; > - char c; > + char c = '\0'; > struct uffd_args args = { 0 }; > args.gopts = gopts; > > @@ -819,7 +819,7 @@ static void > uffd_events_test_common(uffd_global_test_opts_t *gopts, bool wp) > pthread_t uffd_mon; > pid_t pid; > int err; > - char c; > + char c = '\0'; > struct uffd_args args = { 0 }; > args.gopts = gopts; > > @@ -1125,7 +1125,7 @@ uffd_move_test_common(uffd_global_test_opts_t *gopts, > { > unsigned long nr; > pthread_t uffd_mon; > - char c; > + char c = '\0'; > unsigned long long count; > struct uffd_args args = { 0 }; > char *orig_area_src = NULL, *orig_area_dst = NULL; > -- > 2.52.0 > -- Sincerely yours, Mike.
