diff options
| author | Chen Jun <chenjun102@huawei.com> | 2021-09-25 01:44:06 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-09-25 02:13:35 +0300 |
| commit | bcbda81020c3ee77e2c098cadf3e84f99ca3de17 (patch) | |
| tree | 15d5aa803e5d16272dc2dbe348c67aab4939577a | |
| parent | 5c91c0e77b8f2681e2b269c8abb4c5acef434d5b (diff) | |
| download | linux-bcbda81020c3ee77e2c098cadf3e84f99ca3de17.tar.xz | |
mm: fix uninitialized use in overcommit_policy_handler
We get an unexpected value of /proc/sys/vm/overcommit_memory after
running the following program:
int main()
{
int fd = open("/proc/sys/vm/overcommit_memory", O_RDWR);
write(fd, "1", 1);
write(fd, "2", 1);
close(fd);
}
write(fd, "2", 1) will pass *ppos = 1 to proc_dointvec_minmax.
proc_dointvec_minmax will return 0 without setting new_policy.
t.data = &new_policy;
ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos)
-->do_proc_dointvec
-->__do_proc_dointvec
if (write) {
if (proc_first_pos_non_zero_ignore(ppos, table))
goto out;
sysctl_overcommit_memory = new_policy;
so sysctl_overcommit_memory will be set to an uninitialized value.
Check whether new_policy has been changed by proc_dointvec_minmax.
Link: https://lkml.kernel.org/r/20210923020524.13289-1-chenjun102@huawei.com
Fixes: 56f3547bfa4d ("mm: adjust vm_committed_as_batch according to vm overcommit policy")
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Feng Tang <feng.tang@intel.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Rui Xiang <rui.xiang@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/util.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/util.c b/mm/util.c index 499b6b5767ed..bacabe446906 100644 --- a/mm/util.c +++ b/mm/util.c @@ -787,7 +787,7 @@ int overcommit_policy_handler(struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { struct ctl_table t; - int new_policy; + int new_policy = -1; int ret; /* @@ -805,7 +805,7 @@ int overcommit_policy_handler(struct ctl_table *table, int write, void *buffer, t = *table; t.data = &new_policy; ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); - if (ret) + if (ret || new_policy == -1) return ret; mm_compute_batch(new_policy); |