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authorChen Jun <chenjun102@huawei.com>2021-09-25 01:44:06 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-09-25 02:13:35 +0300
commitbcbda81020c3ee77e2c098cadf3e84f99ca3de17 (patch)
tree15d5aa803e5d16272dc2dbe348c67aab4939577a /mm/util.c
parent5c91c0e77b8f2681e2b269c8abb4c5acef434d5b (diff)
downloadlinux-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>
Diffstat (limited to 'mm/util.c')
-rw-r--r--mm/util.c4
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);