kernel/linux.git/fs/f2fs/sysfs.c, branch v6.12.80

f2fs: fix out-of-bounds access in sysfs attribute read/write

2026-02-19T15:29:56+00:00

commit 98ea0039dbfdd00e5cc1b9a8afa40434476c0955 upstream. Some f2fs sysfs attributes suffer from out-of-bounds memory access and incorrect handling of integer values whose size is not 4 bytes. For example: vm:~# echo 65537 > /sys/fs/f2fs/vde/carve_out vm:~# cat /sys/fs/f2fs/vde/carve_out 65537 vm:~# echo 4294967297 > /sys/fs/f2fs/vde/atgc_age_threshold vm:~# cat /sys/fs/f2fs/vde/atgc_age_threshold 1 carve_out maps to {struct f2fs_sb_info}->carve_out, which is a 8-bit integer. However, the sysfs interface allows setting it to a value larger than 255, resulting in an out-of-range update. atgc_age_threshold maps to {struct atgc_management}->age_threshold, which is a 64-bit integer, but its sysfs interface cannot correctly set values larger than UINT_MAX. The root causes are: 1. __sbi_store() treats all default values as unsigned int, which prevents updating integers larger than 4 bytes and causes out-of-bounds writes for integers smaller than 4 bytes. 2. f2fs_sbi_show() also assumes all default values are unsigned int, leading to out-of-bounds reads and incorrect access to integers larger than 4 bytes. This patch introduces {struct f2fs_attr}->size to record the actual size of the integer associated with each sysfs attribute. With this information, sysfs read and write operations can correctly access and update values according to their real data size, avoiding memory corruption and truncation. Fixes: b59d0bae6ca3 ("f2fs: add sysfs support for controlling the gc_thread") Cc: stable@kernel.org Signed-off-by: Jinbao Liu Signed-off-by: Yongpeng Yang Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Greg Kroah-Hartman

f2fs: fix to check sysfs filename w/ gc_pin_file_thresh correctly

2026-02-19T15:29:56+00:00

commit 0eda086de85e140f53c6123a4c00662f4e614ee4 upstream. Sysfs entry name is gc_pin_file_thresh instead of gc_pin_file_threshold, fix it. Cc: stable@kernel.org Fixes: c521a6ab4ad7 ("f2fs: fix to limit gc_pin_file_threshold") Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Greg Kroah-Hartman

f2fs: add gc_boost_gc_greedy sysfs node

2025-12-18T12:55:16+00:00

[ Upstream commit c8705cefce44fbe85ca3b180dee0e0b5f3d51dc5 ] Add this to control GC algorithm for boost GC. Signed-off-by: Daeho Jeong Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Stable-dep-of: e462fc48ceb8 ("f2fs: maintain one time GC mode is enabled during whole zoned GC cycle") Signed-off-by: Sasha Levin

f2fs: add gc_boost_gc_multiple sysfs node

2025-12-18T12:55:16+00:00

[ Upstream commit 1d4c5dbba1a53aeaf2c6cc84e7ba94c436d18852 ] Add a sysfs knob to set a multiplier for the background GC migration window when F2FS Garbage Collection is boosted. Signed-off-by: Daeho Jeong Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Stable-dep-of: e462fc48ceb8 ("f2fs: maintain one time GC mode is enabled during whole zoned GC cycle") Signed-off-by: Sasha Levin

f2fs: introduce reserved_pin_section sysfs entry

2025-12-18T12:55:16+00:00

[ Upstream commit 59c1c89e9ba8cefff05aa982dd9e6719f25e8ec5 ] This patch introduces /sys/fs/f2fs//reserved_pin_section for tuning @needed parameter of has_not_enough_free_secs(), if we configure it w/ zero, it can avoid f2fs_gc() as much as possible while fallocating on pinned file. Signed-off-by: Chao Yu Reviewed-by: wangzijie Signed-off-by: Jaegeuk Kim Stable-dep-of: e462fc48ceb8 ("f2fs: maintain one time GC mode is enabled during whole zoned GC cycle") Signed-off-by: Sasha Levin

f2fs: sysfs: add encoding_flags entry

2025-12-18T12:55:16+00:00

[ Upstream commit 3fea0641b06ff4e53d95d07a96764d8951d4ced6 ] This patch adds a new sysfs entry /sys/fs/f2fs//encoding_flags, it is a read-only entry to show the value of sb.s_encoding_flags, the value is hexadecimal. ============================ ========== Flag_Name Flag_Value ============================ ========== SB_ENC_STRICT_MODE_FL 0x00000001 SB_ENC_NO_COMPAT_FALLBACK_FL 0x00000002 ============================ ========== case#1 mkfs.f2fs -f -O casefold -C utf8:strict /dev/vda mount /dev/vda /mnt/f2fs cat /sys/fs/f2fs/vda/encoding_flags 1 case#2 mkfs.f2fs -f -O casefold -C utf8 /dev/vda fsck.f2fs --nolinear-lookup=1 /dev/vda mount /dev/vda /mnt/f2fs cat /sys/fs/f2fs/vda/encoding_flags 2 Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Stable-dep-of: e462fc48ceb8 ("f2fs: maintain one time GC mode is enabled during whole zoned GC cycle") Signed-off-by: Sasha Levin

f2fs: add carve_out sysfs node

2025-12-18T12:55:15+00:00

[ Upstream commit d7b549def0eb42a950eebd3bd5343f5c8088c305 ] For several zoned storage devices, vendors will provide extra space which was used for device level GC than specs and F2FS can use this space for filesystem level GC. To do that, we can reserve the space using reserved_blocks. However, it is not enough, since this extra space should not be shown to users. So, with this new sysfs node, we can hide the space by substracting reserved_blocks from total bytes. Signed-off-by: Daeho Jeong Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Stable-dep-of: e462fc48ceb8 ("f2fs: maintain one time GC mode is enabled during whole zoned GC cycle") Signed-off-by: Sasha Levin

f2fs: add a sysfs entry to reclaim POSIX_FADV_NOREUSE pages

2025-12-18T12:55:15+00:00

[ Upstream commit a907f3a68ee26ba493a08a958809208d17f3347e ] 1. fadvise(fd1, POSIX_FADV_NOREUSE, {0,3}); 2. fadvise(fd2, POSIX_FADV_NOREUSE, {1,2}); 3. fadvise(fd3, POSIX_FADV_NOREUSE, {3,1}); 4. echo 1024 > /sys/fs/f2fs/tuning/reclaim_caches_kb This gives a way to reclaim file-backed pages by iterating all f2fs mounts until reclaiming 1MB page cache ranges, registered by #1, #2, and #3. 5. cat /sys/fs/f2fs/tuning/reclaim_caches_kb -> gives total number of registered file ranges. Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Stable-dep-of: e462fc48ceb8 ("f2fs: maintain one time GC mode is enabled during whole zoned GC cycle") Signed-off-by: Sasha Levin

f2fs: fix wrong layout information on 16KB page

2025-11-13T20:34:21+00:00

[ Upstream commit a33be64b98d0723748d2fab0832b926613e1fce0 ] This patch fixes to support different block size. Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin

f2fs: fix to check upper boundary for gc_no_zoned_gc_percent

2025-08-15T10:14:01+00:00

[ Upstream commit a919ae794ad2dc6d04b3eea2f9bc86332c1630cc ] This patch adds missing upper boundary check while setting gc_no_zoned_gc_percent via sysfs. Fixes: 9a481a1c16f4 ("f2fs: create gc_no_zoned_gc_percent and gc_boost_zoned_gc_percent") Cc: Daeho Jeong Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin