答复: [PATCH] fs/coredump: reduce redundant log noise in validate_coredump_safety

Li,Rongqing(ACG CCN)
2026-04-22T00:42:25Z

> From: Li RongQing <lirongqing@baidu.com>
>
> Currently, writing to 'core_pattern' or 'suid_dumpable' sysctl nodes always
> triggers validate_coredump_safety(), even if the values have not changed. This
> results in redundant warning messages in dmesg:
>
> "Unsafe core_pattern used with fs.suid_dumpable=2..."
>
> This patch optimizes the procfs handlers to only invoke the safety validation
> when an actual change in the configuration is detected:
>
> 1. In proc_dostring_coredump(), compare the new core_pattern string
> with the existing one using strncmp().
> 2. In proc_dointvec_minmax_coredump(), check if the new suid_dumpable
> value differs from the previous one.
>
> This keeps the kernel log clean from repetitive warnings when re-applying the
> same sysctl settings.
>
> Signed-off-by: Li RongQing <lirongqing@baidu.com>
> ---
> fs/coredump.c | 3 ++-
> fs/exec.c | 6 ++++--
> 2 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/fs/coredump.c b/fs/coredump.c index 29df8aa..9b357d2 100644
> --- a/fs/coredump.c
> +++ b/fs/coredump.c
> @@ -1483,7 +1483,8 @@ static int proc_dostring_coredump(const struct
> ctl_table *table, int write,
> return -EINVAL;
> }
>
> - validate_coredump_safety();
> + if (strncmp(old_core_pattern, core_pattern, CORENAME_MAX_SIZE))
> + validate_coredump_safety();
> return error;
> }
>
> diff --git a/fs/exec.c b/fs/exec.c
> index 9ea3a77..32b46e4 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -1975,9 +1975,11 @@ COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
> static int proc_dointvec_minmax_coredump(const struct ctl_table *table, int
> write,
> void *buffer, size_t *lenp, loff_t *ppos) {
> - int error = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
> + int error, old = READ_ONCE(suid_dumpable);
>
> - if (!error && write)
> + error = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
> +
> + if (!error && write && (old != READ_ONCE(suid_dumpable)))
> validate_coredump_safety();
> return error;
> }
> --
> 2.9.4

Ping
Thanks

[Li,Rongqing]