From 7d20c8abb2edcf962ca857d51f4d0f9cd4b19053 Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Tue, 4 Sep 2018 03:52:17 +0800 Subject: f2fs: fix to avoid NULL pointer dereference on se->discard_map MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Tested-by: Vicente Bergas Signed-off-by: Jaegeuk Kim --- fs/f2fs/debug.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'fs/f2fs/debug.c') 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); -- cgit v1.2.3-58-ga151