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SeongJae Park b0fc14428c mm/damon: implement a function for max nr_accesses safe calculation
commit 35f5d94187a6a3a8df2cba54beccca1c2379edb8 upstream.

Patch series "avoid divide-by-zero due to max_nr_accesses overflow".

The maximum nr_accesses of given DAMON context can be calculated by
dividing the aggregation interval by the sampling interval.  Some logics
in DAMON uses the maximum nr_accesses as a divisor.  Hence, the value
shouldn't be zero.  Such case is avoided since DAMON avoids setting the
agregation interval as samller than the sampling interval.  However, since
nr_accesses is unsigned int while the intervals are unsigned long, the
maximum nr_accesses could be zero while casting.

Avoid the divide-by-zero by implementing a function that handles the
corner case (first patch), and replaces the vulnerable direct max
nr_accesses calculations (remaining patches).

Note that the patches for the replacements are divided for broken commits,
to make backporting on required tres easier.  Especially, the last patch
is for a patch that not yet merged into the mainline but in mm tree.


This patch (of 4):

The maximum nr_accesses of given DAMON context can be calculated by
dividing the aggregation interval by the sampling interval.  Some logics
in DAMON uses the maximum nr_accesses as a divisor.  Hence, the value
shouldn't be zero.  Such case is avoided since DAMON avoids setting the
agregation interval as samller than the sampling interval.  However, since
nr_accesses is unsigned int while the intervals are unsigned long, the
maximum nr_accesses could be zero while casting.  Implement a function
that handles the corner case.

Note that this commit is not fixing the real issue since this is only
introducing the safe function that will replaces the problematic
divisions.  The replacements will be made by followup commits, to make
backporting on stable series easier.

Link: https://lkml.kernel.org/r/20231019194924.100347-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20231019194924.100347-2-sj@kernel.org
Fixes: 198f0f4c58 ("mm/damon/vaddr,paddr: support pageout prioritization")
Signed-off-by: SeongJae Park <sj@kernel.org>
Reported-by: Jakub Acs <acsjakub@amazon.de>
Cc: <stable@vger.kernel.org>	[5.16+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-11-28 17:07:09 +00:00
arch KVM: x86: Clear bit12 of ICR after APIC-write VM-exit 2023-11-28 17:07:08 +00:00
block blk-core: use pr_warn_ratelimited() in bio_check_ro() 2023-11-20 11:52:17 +01:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: pcrypt - Fix hungtask for PADATA_RESET 2023-11-28 17:06:58 +00:00
Documentation smp,csd: Throw an error if a CSD lock is stuck for too long 2023-11-28 17:06:55 +00:00
drivers PCI/sysfs: Protect driver's D3cold preference from user space 2023-11-28 17:07:08 +00:00
fs watchdog: move softlockup_panic back to early_param 2023-11-28 17:07:09 +00:00
include mm/damon: implement a function for max nr_accesses safe calculation 2023-11-28 17:07:09 +00:00
init proc: sysctl: prevent aliased sysctls from getting passed to init 2023-11-28 17:07:08 +00:00
io_uring io_uring/net: ensure socket is marked connected on connect retry 2023-11-20 11:52:18 +01:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel watchdog: move softlockup_panic back to early_param 2023-11-28 17:07:09 +00:00
lib lib/generic-radix-tree.c: Don't overflow in peek() 2023-11-28 17:06:54 +00:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm/damon/ops-common: avoid divide-by-zero during region hotness calculation 2023-11-28 17:07:09 +00:00
net netfilter: nf_tables: fix pointer math issue in nft_byteorder_eval() 2023-11-28 17:07:05 +00:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples fprobe: Pass entry_data to handlers 2023-10-25 12:03:12 +02:00
scripts randstruct: Fix gcc-plugin performance mode to stay in group 2023-11-28 17:07:07 +00:00
security apparmor: fix invalid reference on profile->disconnected 2023-11-20 11:52:09 +01:00
sound ALSA: hda/realtek: Add quirk for ASUS UX7602ZM 2023-11-28 17:07:03 +00:00
tools perf intel-pt: Fix async branch flags 2023-11-28 17:07:07 +00:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add() 2023-09-13 09:42:46 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig
MAINTAINERS devlink: move code to a dedicated directory 2023-08-30 16:11:00 +02:00
Makefile Linux 6.1.63 2023-11-20 11:52:19 +01:00
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Linux kernel
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