* + sysctlc-fix-underflow-value-setting-risk-in-vm_table.patch added to -mm tree
@ 2020-12-23 20:22 akpm
0 siblings, 0 replies; only message in thread
From: akpm @ 2020-12-23 20:22 UTC (permalink / raw)
To: mm-commits, ebiederm, adobriyan, linf
The patch titled
Subject: sysctl.c: fix underflow value setting risk in vm_table
has been added to the -mm tree. Its filename is
sysctlc-fix-underflow-value-setting-risk-in-vm_table.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/sysctlc-fix-underflow-value-setting-risk-in-vm_table.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/sysctlc-fix-underflow-value-setting-risk-in-vm_table.patch
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From: Lin Feng <linf@wangsu.com>
Subject: sysctl.c: fix underflow value setting risk in vm_table
Apart from subsystem specific .proc_handler handler, all ctl_tables with
extra1 and extra2 members set should use proc_dointvec_minmax instead of
proc_dointvec, or the limit set in extra* never work and potentially echo
underflow values(negative numbers) is likely make system unstable.
Especially vfs_cache_pressure and zone_reclaim_mode, -1 is apparently not
a valid value, but we can set to them. And then kernel may crash.
# echo -1 > /proc/sys/vm/vfs_cache_pressure
Link: https://lkml.kernel.org/r/20201223105535.2875-1-linf@wangsu.com
Signed-off-by: Lin Feng <linf@wangsu.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
kernel/sysctl.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/kernel/sysctl.c~sysctlc-fix-underflow-value-setting-risk-in-vm_table
+++ a/kernel/sysctl.c
@@ -2962,7 +2962,7 @@ static struct ctl_table vm_table[] = {
.data = &block_dump,
.maxlen = sizeof(block_dump),
.mode = 0644,
- .proc_handler = proc_dointvec,
+ .proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
},
{
@@ -2970,7 +2970,7 @@ static struct ctl_table vm_table[] = {
.data = &sysctl_vfs_cache_pressure,
.maxlen = sizeof(sysctl_vfs_cache_pressure),
.mode = 0644,
- .proc_handler = proc_dointvec,
+ .proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
},
#if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \
@@ -2980,7 +2980,7 @@ static struct ctl_table vm_table[] = {
.data = &sysctl_legacy_va_layout,
.maxlen = sizeof(sysctl_legacy_va_layout),
.mode = 0644,
- .proc_handler = proc_dointvec,
+ .proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
},
#endif
@@ -2990,7 +2990,7 @@ static struct ctl_table vm_table[] = {
.data = &node_reclaim_mode,
.maxlen = sizeof(node_reclaim_mode),
.mode = 0644,
- .proc_handler = proc_dointvec,
+ .proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
},
{
_
Patches currently in -mm which might be from linf@wangsu.com are
sysctlc-fix-underflow-value-setting-risk-in-vm_table.patch
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