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sysctl.c: fix underflow value setting risk in vm_table

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[ Upstream commit 3b3376f222e3ab58367d9dd405cafd09d5e37b7c ]

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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Lin Feng 2021-02-25 17:20:53 -08:00 committed by Greg Kroah-Hartman
parent 508d56e2c5
commit acf0e7b15f
1 changed files with 4 additions and 4 deletions
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8
kernel/sysctl.c
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@ -1563,7 +1563,7 @@ 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,
},
{
@ -1571,7 +1571,7 @@ 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) || \
@ -1581,7 +1581,7 @@ 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
@ -1591,7 +1591,7 @@ 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,
},
{