| Message ID | 20210922014122.47219-1-chenjun102@huawei.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2,1/1] mm: Fix the uninitialized use in overcommit_policy_handler | expand |
On Wed 22-09-21 01:41:22, Chen Jun wrote: > An unexpected value of /proc/sys/vm/panic_on_oom we will get, > after running the following program. > > int main() > { > int fd = open("/proc/sys/vm/panic_on_oom", 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. > > 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> Btw. you could also check for new_policy == sysctl_overcommit_memory so that the sync of pcp counters is not fired without the policy change. Something for a separate patch I guess. > --- > > v2: > * Check whether new_policy has been changed by proc_dointvec_minmax. > > mm/util.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/util.c b/mm/util.c > index 4ddb6e186dd5..d5be67771850 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -756,7 +756,7 @@ 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; > > /* > @@ -774,7 +774,7 @@ 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); > -- > 2.17.1
Hi Jun, On Wed, Sep 22, 2021 at 01:41:22AM +0000, Chen Jun wrote: > An unexpected value of /proc/sys/vm/panic_on_oom we will get, > after running the following program. > > int main() > { > int fd = open("/proc/sys/vm/panic_on_oom", O_RDWR) should this be "/proc/sys/vm/overcommit_memory" > 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. Other than the nit above, it looks good to me, thanks! Reviewed-by: Feng Tang <feng.tang@intel.com> > Fixes: 56f3547bfa4d ("mm: adjust vm_committed_as_batch according to vm overcommit policy" > Signed-off-by: Chen Jun <chenjun102@huawei.com> > --- > > v2: > * Check whether new_policy has been changed by proc_dointvec_minmax. > > mm/util.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/util.c b/mm/util.c > index 4ddb6e186dd5..d5be67771850 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -756,7 +756,7 @@ 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; > > /* > @@ -774,7 +774,7 @@ 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); > -- > 2.17.1 >
Hi Tang, 在 2021/9/22 23:34, Feng Tang 写道: > Hi Jun, > > On Wed, Sep 22, 2021 at 01:41:22AM +0000, Chen Jun wrote: >> An unexpected value of /proc/sys/vm/panic_on_oom we will get, >> after running the following program. >> >> int main() >> { >> int fd = open("/proc/sys/vm/panic_on_oom", O_RDWR) > > should this be "/proc/sys/vm/overcommit_memory" > Sorry, that is my mistake, I will correct it in v3. Thanks. >> 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. > > Other than the nit above, it looks good to me, thanks! > > Reviewed-by: Feng Tang <feng.tang@intel.com> > >> Fixes: 56f3547bfa4d ("mm: adjust vm_committed_as_batch according to vm overcommit policy" >> Signed-off-by: Chen Jun <chenjun102@huawei.com> >> --- >> >> v2: >> * Check whether new_policy has been changed by proc_dointvec_minmax. >> >> mm/util.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/mm/util.c b/mm/util.c >> index 4ddb6e186dd5..d5be67771850 100644 >> --- a/mm/util.c >> +++ b/mm/util.c >> @@ -756,7 +756,7 @@ 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; >> >> /* >> @@ -774,7 +774,7 @@ 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); >> -- >> 2.17.1 >> >
diff --git a/mm/util.c b/mm/util.c index 4ddb6e186dd5..d5be67771850 100644 --- a/mm/util.c +++ b/mm/util.c @@ -756,7 +756,7 @@ 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; /* @@ -774,7 +774,7 @@ 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);
An unexpected value of /proc/sys/vm/panic_on_oom we will get, after running the following program. int main() { int fd = open("/proc/sys/vm/panic_on_oom", 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. Fixes: 56f3547bfa4d ("mm: adjust vm_committed_as_batch according to vm overcommit policy" Signed-off-by: Chen Jun <chenjun102@huawei.com> --- v2: * Check whether new_policy has been changed by proc_dointvec_minmax. mm/util.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)