From: Li RongQing 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 --- 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