[PATCH AUTOSEL 4.19 04/57] f2fs: fix to avoid NULL pointer dereference on se->discard_map

Sasha Levin
2019-03-30T01:29:06Z

From: Chao Yu <yuchao0@huawei.com>

[ Upstream commit 7d20c8abb2edcf962ca857d51f4d0f9cd4b19053 ]

https://bugzilla.kernel.org/show_bug.cgi?id=200951

These is a NULL pointer dereference issue reported in bugzilla:

Hi,
in the setup there is a SATA SSD connected to a SATA-to-USB bridge.

The disc is "Samsung SSD 850 PRO 256G" which supports TRIM.
There are four partitions:
sda1: FAT /boot
sda2: F2FS /
sda3: F2FS /home
sda4: F2FS

The bridge is ASMT1153e which uses the "uas" driver.
There is no TRIM pass-through, so, when mounting it reports:
mounting with "discard" option, but the device does not support discard

The USB host is USB3.0 and UASP capable. It is the one on RK3399.

Given this everything works fine, except there is no TRIM support.

In order to enable TRIM a new UDEV rule is added [1]:
/etc/udev/rules.d/10-sata-bridge-trim.rules:
ACTION=="add|change", ATTRS{idVendor}=="174c", ATTRS{idProduct}=="55aa", SUBSYSTEM=="scsi_disk", ATTR{provisioning_mode}="unmap"
After reboot any F2FS write hangs forever and dmesg reports:
Unable to handle kernel NULL pointer dereference

Also tested on a x86_64 system: works fine even with TRIM enabled.
same disc
same bridge
different usb host controller
different cpu architecture
not root filesystem

Regards,
Vicenç.

[1] Post #5 in https://bbs.archlinux.org/viewtopic.php?id=236280

Unable to handle kernel NULL pointer dereference at virtual address 000000000000003e
Mem abort info:
ESR = 0x96000004
Exception class = DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
Data abort info:
ISV = 0, ISS = 0x00000004
CM = 0, WnR = 0
user pgtable: 4k pages, 48-bit VAs, pgdp = 00000000626e3122
[000000000000003e] pgd=0000000000000000
Internal error: Oops: 96000004 [#1] SMP
Modules linked in: overlay snd_soc_hdmi_codec rc_cec dw_hdmi_i2s_audio dw_hdmi_cec snd_soc_simple_card snd_soc_simple_card_utils snd_soc_rockchip_i2s rockchip_rga snd_soc_rockchip_pcm rockchipdrm videobuf2_dma_sg v4l2_mem2mem rtc_rk808 videobuf2_memops analogix_dp videobuf2_v4l2 videobuf2_common dw_hdmi dw_wdt cec rc_core videodev drm_kms_helper media drm rockchip_thermal rockchip_saradc realtek drm_panel_orientation_quirks syscopyarea sysfillrect sysimgblt fb_sys_fops dwmac_rk stmmac_platform stmmac pwm_bl squashfs loop crypto_user gpio_keys hid_kensington
CPU: 5 PID: 957 Comm: nvim Not tainted 4.19.0-rc1-1-ARCH #1
Hardware name: Sapphire-RK3399 Board (DT)
pstate: 00000005 (nzcv daif -PAN -UAO)
pc : update_sit_entry+0x304/0x4b0
lr : update_sit_entry+0x108/0x4b0
sp : ffff00000ca13bd0
x29: ffff00000ca13bd0 x28: 000000000000003e
x27: 0000000000000020 x26: 0000000000080000
x25: 0000000000000048 x24: ffff8000ebb85cf8
x23: 0000000000000253 x22: 00000000ffffffff
x21: 00000000000535f2 x20: 00000000ffffffdf
x19: ffff8000eb9e6800 x18: ffff8000eb9e6be8
x17: 0000000007ce6926 x16: 000000001c83ffa8
x15: 0000000000000000 x14: ffff8000f602df90
x13: 0000000000000006 x12: 0000000000000040
x11: 0000000000000228 x10: 0000000000000000
x9 : 0000000000000000 x8 : 0000000000000000
x7 : 00000000000535f2 x6 : ffff8000ebff3440
x5 : ffff8000ebff3440 x4 : ffff8000ebe3a6c8
x3 : 00000000ffffffff x2 : 0000000000000020
x1 : 0000000000000000 x0 : ffff8000eb9e5800
Process nvim (pid: 957, stack limit = 0x0000000063a78320)
Call trace:
update_sit_entry+0x304/0x4b0
f2fs_invalidate_blocks+0x98/0x140
truncate_node+0x90/0x400
f2fs_remove_inode_page+0xe8/0x340
f2fs_evict_inode+0x2b0/0x408
evict+0xe0/0x1e0
iput+0x160/0x260
do_unlinkat+0x214/0x298
__arm64_sys_unlinkat+0x3c/0x68
el0_svc_handler+0x94/0x118
el0_svc+0x8/0xc
Code: f9400800 b9488400 36080140 f9400f01 (387c4820)
---[ end trace a0f21a307118c477 ]---

The reason is it is possible to enable discard flag on block queue via
UDEV, but during mount, f2fs will initialize se->discard_map only if
this flag is set, once the flag is set after mount, f2fs may dereference
NULL pointer on se->discard_map.

So this patch does below changes to fix this issue:
- initialize and update se->discard_map all the time.
- don't clear DISCARD option if device has no QUEUE_FLAG_DISCARD flag
during mount.
- don't issue small discard on zoned block device.
- introduce some functions to enhance the readability.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Tested-by: Vicente Bergas <vicencb@gmail.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/f2fs/debug.c | 3 +--
fs/f2fs/f2fs.h | 15 ++++++++---
fs/f2fs/file.c | 2 +-
fs/f2fs/segment.c | 65 ++++++++++++++++++++---------------------------
fs/f2fs/super.c | 16 +++---------
5 files changed, 46 insertions(+), 55 deletions(-)

diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
index 214a968962a1..ebe649d9793c 100644
--- a/fs/f2fs/debug.c
+++ b/fs/f2fs/debug.c
@@ -190,8 +190,7 @@ static void update_mem_info(struct f2fs_sb_info *sbi)
si->base_mem += MAIN_SEGS(sbi) * sizeof(struct seg_entry);
si->base_mem += f2fs_bitmap_size(MAIN_SEGS(sbi));
si->base_mem += 2 * SIT_VBLOCK_MAP_SIZE * MAIN_SEGS(sbi);
- if (f2fs_discard_en(sbi))
- si->base_mem += SIT_VBLOCK_MAP_SIZE * MAIN_SEGS(sbi);
+ si->base_mem += SIT_VBLOCK_MAP_SIZE * MAIN_SEGS(sbi);
si->base_mem += SIT_VBLOCK_MAP_SIZE;
if (sbi->segs_per_sec > 1)
si->base_mem += MAIN_SECS(sbi) * sizeof(struct sec_entry);
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 42aef5c94927..19d2bbaf4c25 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -3410,11 +3410,20 @@ static inline int get_blkz_type(struct f2fs_sb_info *sbi,
}
#endif

-static inline bool f2fs_discard_en(struct f2fs_sb_info *sbi)
+static inline bool f2fs_hw_should_discard(struct f2fs_sb_info *sbi)
{
- struct request_queue *q = bdev_get_queue(sbi->sb->s_bdev);
+ return f2fs_sb_has_blkzoned(sbi->sb);
+}

- return blk_queue_discard(q) || f2fs_sb_has_blkzoned(sbi->sb);
+static inline bool f2fs_hw_support_discard(struct f2fs_sb_info *sbi)
+{
+ return blk_queue_discard(bdev_get_queue(sbi->sb->s_bdev));
+}
+
+static inline bool f2fs_realtime_discard_enable(struct f2fs_sb_info *sbi)
+{
+ return (test_opt(sbi, DISCARD) && f2fs_hw_support_discard(sbi)) ||
+ f2fs_hw_should_discard(sbi);
}

static inline void set_opt_mode(struct f2fs_sb_info *sbi, unsigned int mt)
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 81c1dd635a8d..9fc076ca002d 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1983,7 +1983,7 @@ static int f2fs_ioc_fitrim(struct file *filp, unsigned long arg)
if (!capable(CAP_SYS_ADMIN))
return -EPERM;

- if (!blk_queue_discard(q))
+ if (!f2fs_hw_support_discard(F2FS_SB(sb)))
return -EOPNOTSUPP;

if (copy_from_user(&range, (struct fstrim_range __user *)arg,
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 1fa6f8185766..ac038563273d 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1744,11 +1744,11 @@ static bool add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc,
struct list_head *head = &SM_I(sbi)->dcc_info->entry_list;
int i;

- if (se->valid_blocks == max_blocks || !f2fs_discard_en(sbi))
+ if (se->valid_blocks == max_blocks || !f2fs_hw_support_discard(sbi))
return false;

if (!force) {
- if (!test_opt(sbi, DISCARD) || !se->valid_blocks ||
+ if (!f2fs_realtime_discard_enable(sbi) || !se->valid_blocks ||
SM_I(sbi)->dcc_info->nr_discards >=
SM_I(sbi)->dcc_info->max_discards)
return false;
@@ -1854,7 +1854,7 @@ void f2fs_clear_prefree_segments(struct f2fs_sb_info *sbi,
dirty_i->nr_dirty[PRE]--;
}

- if (!test_opt(sbi, DISCARD))
+ if (!f2fs_realtime_discard_enable(sbi))
continue;

if (force && start >= cpc->trim_start &&
@@ -2044,8 +2044,7 @@ static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del)
del = 0;
}

- if (f2fs_discard_en(sbi) &&
- !f2fs_test_and_set_bit(offset, se->discard_map))
+ if (!f2fs_test_and_set_bit(offset, se->discard_map))
sbi->discard_blks--;

/* don't overwrite by SSR to keep node chain */
@@ -2073,8 +2072,7 @@ static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del)
del = 0;
}

- if (f2fs_discard_en(sbi) &&
- f2fs_test_and_clear_bit(offset, se->discard_map))
+ if (f2fs_test_and_clear_bit(offset, se->discard_map))
sbi->discard_blks++;
}
if (!f2fs_test_bit(offset, se->ckpt_valid_map))
@@ -2690,7 +2688,7 @@ int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
* discard option. User configuration looks like using runtime discard
* or periodic fstrim instead of it.
*/
- if (test_opt(sbi, DISCARD))
+ if (f2fs_realtime_discard_enable(sbi))
goto out;

start_block = START_BLOCK(sbi, start_segno);
@@ -3781,13 +3779,11 @@ static int build_sit_info(struct f2fs_sb_info *sbi)
return -ENOMEM;
#endif

- if (f2fs_discard_en(sbi)) {
- sit_i->sentries[start].discard_map
- = f2fs_kzalloc(sbi, SIT_VBLOCK_MAP_SIZE,
- GFP_KERNEL);
- if (!sit_i->sentries[start].discard_map)
- return -ENOMEM;
- }
+ sit_i->sentries[start].discard_map
+ = f2fs_kzalloc(sbi, SIT_VBLOCK_MAP_SIZE,
+ GFP_KERNEL);
+ if (!sit_i->sentries[start].discard_map)
+ return -ENOMEM;
}

sit_i->tmp_map = f2fs_kzalloc(sbi, SIT_VBLOCK_MAP_SIZE, GFP_KERNEL);
@@ -3935,18 +3931,16 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
total_node_blocks += se->valid_blocks;

/* build discard map only one time */
- if (f2fs_discard_en(sbi)) {
- if (is_set_ckpt_flags(sbi, CP_TRIMMED_FLAG)) {
- memset(se->discard_map, 0xff,
- SIT_VBLOCK_MAP_SIZE);
- } else {
- memcpy(se->discard_map,
- se->cur_valid_map,
- SIT_VBLOCK_MAP_SIZE);
- sbi->discard_blks +=
- sbi->blocks_per_seg -
- se->valid_blocks;
- }
+ if (is_set_ckpt_flags(sbi, CP_TRIMMED_FLAG)) {
+ memset(se->discard_map, 0xff,
+ SIT_VBLOCK_MAP_SIZE);
+ } else {
+ memcpy(se->discard_map,
+ se->cur_valid_map,
+ SIT_VBLOCK_MAP_SIZE);
+ sbi->discard_blks +=
+ sbi->blocks_per_seg -
+ se->valid_blocks;
}

if (sbi->segs_per_sec > 1)
@@ -3984,16 +3978,13 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
if (IS_NODESEG(se->type))
total_node_blocks += se->valid_blocks;

- if (f2fs_discard_en(sbi)) {
- if (is_set_ckpt_flags(sbi, CP_TRIMMED_FLAG)) {
- memset(se->discard_map, 0xff,
- SIT_VBLOCK_MAP_SIZE);
- } else {
- memcpy(se->discard_map, se->cur_valid_map,
- SIT_VBLOCK_MAP_SIZE);
- sbi->discard_blks += old_valid_blocks;
- sbi->discard_blks -= se->valid_blocks;
- }
+ if (is_set_ckpt_flags(sbi, CP_TRIMMED_FLAG)) {
+ memset(se->discard_map, 0xff, SIT_VBLOCK_MAP_SIZE);
+ } else {
+ memcpy(se->discard_map, se->cur_valid_map,
+ SIT_VBLOCK_MAP_SIZE);
+ sbi->discard_blks += old_valid_blocks;
+ sbi->discard_blks -= se->valid_blocks;
}

if (sbi->segs_per_sec > 1) {
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index c9639ef0e8d5..ec50b95c7ea5 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -360,7 +360,6 @@ static int f2fs_check_quota_options(struct f2fs_sb_info *sbi)
static int parse_options(struct super_block *sb, char *options)
{
struct f2fs_sb_info *sbi = F2FS_SB(sb);
- struct request_queue *q;
substring_t args[MAX_OPT_ARGS];
char *p, *name;
int arg = 0;
@@ -415,14 +414,7 @@ static int parse_options(struct super_block *sb, char *options)
return -EINVAL;
break;
case Opt_discard:
- q = bdev_get_queue(sb->s_bdev);
- if (blk_queue_discard(q)) {
- set_opt(sbi, DISCARD);
- } else if (!f2fs_sb_has_blkzoned(sb)) {
- f2fs_msg(sb, KERN_WARNING,
- "mounting with \"discard\" option, but "
- "the device does not support discard");
- }
+ set_opt(sbi, DISCARD);
break;
case Opt_nodiscard:
if (f2fs_sb_has_blkzoned(sb)) {
@@ -1032,7 +1024,8 @@ static void f2fs_put_super(struct super_block *sb)
/* be sure to wait for any on-going discard commands */
dropped = f2fs_wait_discard_bios(sbi);

- if (f2fs_discard_en(sbi) && !sbi->discard_blks && !dropped) {
+ if ((f2fs_hw_support_discard(sbi) || f2fs_hw_should_discard(sbi)) &&
+ !sbi->discard_blks && !dropped) {
struct cp_control cpc = {
.reason = CP_UMOUNT | CP_TRIMMED,
};
@@ -1402,8 +1395,7 @@ static void default_options(struct f2fs_sb_info *sbi)
set_opt(sbi, NOHEAP);
sbi->sb->s_flags |= SB_LAZYTIME;
set_opt(sbi, FLUSH_MERGE);
- if (blk_queue_discard(bdev_get_queue(sbi->sb->s_bdev)))
- set_opt(sbi, DISCARD);
+ set_opt(sbi, DISCARD);
if (f2fs_sb_has_blkzoned(sbi->sb))
set_opt_mode(sbi, F2FS_MOUNT_LFS);
else
--
2.19.1