From: Yafang Shao <laoar.shao@gmail.com>
To: akpm@linux-foundation.org, keescook@chromium.org,
rostedt@goodmis.org, mathieu.desnoyers@efficios.com,
arnaldo.melo@gmail.com, pmladek@suse.com, peterz@infradead.org,
viro@zeniv.linux.org.uk, valentin.schneider@arm.com,
qiang.zhang@windriver.com, robdclark@chromium.org,
christian@brauner.io, dietmar.eggemann@arm.com, mingo@redhat.com,
juri.lelli@redhat.com, vincent.guittot@linaro.org,
davem@davemloft.net, kuba@kernel.org, ast@kernel.org,
daniel@iogearbox.net, andrii@kernel.org, kafai@fb.com,
songliubraving@fb.com, yhs@fb.com, john.fastabend@gmail.com,
kpsingh@kernel.org, dennis.dalessandro@cornelisnetworks.com,
mike.marciniszyn@cornelisnetworks.com, dledford@redhat.com,
jgg@ziepe.ca
Cc: linux-rdma@vger.kernel.org, netdev@vger.kernel.org,
bpf@vger.kernel.org, linux-perf-users@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, oliver.sang@intel.com,
lkp@intel.com, Yafang Shao <laoar.shao@gmail.com>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Andrii Nakryiko <andrii.nakryiko@gmail.com>
Subject: [PATCH v7 03/11] sched.h: use __must_be_array instead of BUILD_BUG_ON in get_task_comm
Date: Mon, 1 Nov 2021 06:04:11 +0000 [thread overview]
Message-ID: <20211101060419.4682-4-laoar.shao@gmail.com> (raw)
In-Reply-To: <20211101060419.4682-1-laoar.shao@gmail.com>
Now that __get_task_comm() will truncate and pad, it's safe to use on both
too-small and too-big arrays. So it is not needed to check array length
any more. For the original goal of making sure get_task_comm() is being
used on a char array, we can use __must_be_array().
Below is the verification when I changed the dest buffer of
get_task_comm() in a driver code,
CC [M] drivers/infiniband/hw/qib/qib_file_ops.o
In file included from ./include/linux/bits.h:22:0,
from ./include/linux/ioport.h:13,
from ./include/linux/pci.h:31,
from drivers/infiniband/hw/qib/qib_file_ops.c:35:
drivers/infiniband/hw/qib/qib_file_ops.c: In function ‘setup_ctxt’:
./include/linux/build_bug.h:16:51: error: negative width in bit-field ‘<anonymous>’
#define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
^
./include/linux/compiler.h:258:28: note: in expansion of macro ‘BUILD_BUG_ON_ZERO’
#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
^~~~~~~~~~~~~~~~~
./include/linux/sched.h:1941:23: note: in expansion of macro ‘__must_be_array’
__get_task_comm(buf, __must_be_array(buf) + sizeof(buf), tsk)
^~~~~~~~~~~~~~~
drivers/infiniband/hw/qib/qib_file_ops.c:1325:2: note: in expansion of macro ‘get_task_comm’
get_task_comm(test, current);
It hit this warnig as expected.
Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Petr Mladek <pmladek@suse.com>
---
include/linux/sched.h | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index c1a927ddec64..b9c85c52fed0 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1931,10 +1931,8 @@ static inline void set_task_comm(struct task_struct *tsk, const char *from)
}
extern char *__get_task_comm(char *to, size_t len, struct task_struct *tsk);
-#define get_task_comm(buf, tsk) ({ \
- BUILD_BUG_ON(sizeof(buf) != TASK_COMM_LEN); \
- __get_task_comm(buf, sizeof(buf), tsk); \
-})
+#define get_task_comm(buf, tsk) \
+ __get_task_comm(buf, __must_be_array(buf) + sizeof(buf), tsk)
#ifdef CONFIG_SMP
static __always_inline void scheduler_ipi(void)
--
2.17.1
next prev parent reply other threads:[~2021-11-01 6:04 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-01 6:04 [PATCH v7 00/11] extend task comm from 16 to 24 Yafang Shao
2021-11-01 6:04 ` [PATCH v7 01/11] fs/exec: make __set_task_comm always set a nul terminated string Yafang Shao
2021-11-01 6:04 ` [PATCH v7 02/11] fs/exec: make __get_task_comm always get " Yafang Shao
2021-11-01 6:04 ` Yafang Shao [this message]
2021-11-01 6:04 ` [PATCH v7 04/11] drivers/infiniband: make setup_ctxt always get a nul terminated task comm Yafang Shao
2021-11-01 6:04 ` [PATCH v7 05/11] fs/binfmt_elf: make prpsinfo " Yafang Shao
2021-11-01 6:04 ` [PATCH v7 06/11] samples/bpf/test_overhead_kprobe_kern: make it adopt to task comm size change Yafang Shao
2021-11-01 6:04 ` [PATCH v7 07/11] tools/bpf/bpftool/skeleton: " Yafang Shao
2021-11-01 23:47 ` Andrii Nakryiko
2021-11-01 6:04 ` [PATCH v7 08/11] tools/perf/test: make perf test " Yafang Shao
2021-11-17 14:31 ` Arnaldo Carvalho de Melo
2021-11-18 14:18 ` Yafang Shao
2021-11-01 6:04 ` [PATCH v7 09/11] tools/testing/selftests/bpf: make it " Yafang Shao
2021-11-01 23:47 ` Andrii Nakryiko
2021-11-01 6:04 ` [PATCH v7 10/11] sched.h: extend task comm from 16 to 24 Yafang Shao
2021-11-01 6:04 ` [PATCH v7 11/11] kernel/kthread: show a warning if kthread's comm is truncated Yafang Shao
2021-11-01 12:44 ` [PATCH v7 00/11] extend task comm from 16 to 24 Matthew Wilcox
2021-11-01 13:12 ` Yafang Shao
2021-11-01 14:07 ` Petr Mladek
2021-11-01 14:34 ` Yafang Shao
2021-11-01 16:02 ` Petr Mladek
2021-11-01 16:06 ` Steven Rostedt
2021-11-02 1:09 ` Yafang Shao
2021-11-02 1:18 ` Steven Rostedt
2021-11-02 1:26 ` Yafang Shao
2021-11-02 7:56 ` Petr Mladek
2021-11-02 13:48 ` Yafang Shao
2021-11-02 9:26 ` David Hildenbrand
2021-11-04 1:37 ` Michał Mirosław
2021-11-05 6:34 ` Yafang Shao
2021-11-05 23:57 ` Michał Mirosław
2021-11-06 9:12 ` Yafang Shao
2021-11-06 11:29 ` Michał Mirosław
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