From: Yongpeng Yang yangyongpeng@xiaomi.com

When emulating an nvme device on qemu with both logical_block_size and physical_block_size set to 8 KiB, but without format, a kernel panic was triggered during the early boot stage while attempting to mount a vfat filesystem.

[95553.682035] EXT4-fs (nvme0n1): unable to set blocksize [95553.684326] EXT4-fs (nvme0n1): unable to set blocksize [95553.686501] EXT4-fs (nvme0n1): unable to set blocksize [95553.696448] ISOFS: unsupported/invalid hardware sector size 8192 [95553.697117] ------------[ cut here ]------------ [95553.697567] kernel BUG at fs/buffer.c:1582! [95553.697984] Oops: invalid opcode: 0000 [#1] SMP NOPTI [95553.698602] CPU: 0 UID: 0 PID: 7212 Comm: mount Kdump: loaded Not tainted 6.18.0-rc2+ #38 PREEMPT(voluntary) [95553.699511] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [95553.700534] RIP: 0010:folio_alloc_buffers+0x1bb/0x1c0 [95553.701018] Code: 48 8b 15 e8 93 18 02 65 48 89 35 e0 93 18 02 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d 31 d2 31 c9 31 f6 31 ff c3 cc cc cc cc <0f> 0b 90 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f [95553.702648] RSP: 0018:ffffd1b0c676f990 EFLAGS: 00010246 [95553.703132] RAX: ffff8cfc4176d820 RBX: 0000000000508c48 RCX: 0000000000000001 [95553.703805] RDX: 0000000000002000 RSI: 0000000000000000 RDI: 0000000000000000 [95553.704481] RBP: ffffd1b0c676f9c8 R08: 0000000000000000 R09: 0000000000000000 [95553.705148] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 [95553.705816] R13: 0000000000002000 R14: fffff8bc8257e800 R15: 0000000000000000 [95553.706483] FS: 000072ee77315840(0000) GS:ffff8cfdd2c8d000(0000) knlGS:0000000000000000 [95553.707248] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [95553.707782] CR2: 00007d8f2a9e5a20 CR3: 0000000039d0c006 CR4: 0000000000772ef0 [95553.708439] PKRU: 55555554 [95553.708734] Call Trace: [95553.709015] <TASK> [95553.709266] __getblk_slow+0xd2/0x230 [95553.709641] ? find_get_block_common+0x8b/0x530 [95553.710084] bdev_getblk+0x77/0xa0 [95553.710449] __bread_gfp+0x22/0x140 [95553.710810] fat_fill_super+0x23a/0xfc0 [95553.711216] ? __pfx_setup+0x10/0x10 [95553.711580] ? __pfx_vfat_fill_super+0x10/0x10 [95553.712014] vfat_fill_super+0x15/0x30 [95553.712401] get_tree_bdev_flags+0x141/0x1e0 [95553.712817] get_tree_bdev+0x10/0x20 [95553.713177] vfat_get_tree+0x15/0x20 [95553.713550] vfs_get_tree+0x2a/0x100 [95553.713910] vfs_cmd_create+0x62/0xf0 [95553.714273] __do_sys_fsconfig+0x4e7/0x660 [95553.714669] __x64_sys_fsconfig+0x20/0x40 [95553.715062] x64_sys_call+0x21ee/0x26a0 [95553.715453] do_syscall_64+0x80/0x670 [95553.715816] ? __fs_parse+0x65/0x1e0 [95553.716172] ? fat_parse_param+0x103/0x4b0 [95553.716587] ? vfs_parse_fs_param_source+0x21/0xa0 [95553.717034] ? __do_sys_fsconfig+0x3d9/0x660 [95553.717548] ? __x64_sys_fsconfig+0x20/0x40 [95553.717957] ? x64_sys_call+0x21ee/0x26a0 [95553.718360] ? do_syscall_64+0xb8/0x670 [95553.718734] ? __x64_sys_fsconfig+0x20/0x40 [95553.719141] ? x64_sys_call+0x21ee/0x26a0 [95553.719545] ? do_syscall_64+0xb8/0x670 [95553.719922] ? x64_sys_call+0x1405/0x26a0 [95553.720317] ? do_syscall_64+0xb8/0x670 [95553.720702] ? __x64_sys_close+0x3e/0x90 [95553.721080] ? x64_sys_call+0x1b5e/0x26a0 [95553.721478] ? do_syscall_64+0xb8/0x670 [95553.721841] ? irqentry_exit+0x43/0x50 [95553.722211] ? exc_page_fault+0x90/0x1b0 [95553.722681] entry_SYSCALL_64_after_hwframe+0x76/0x7e [95553.723166] RIP: 0033:0x72ee774f3afe [95553.723562] Code: 73 01 c3 48 8b 0d 0a 33 0f 00 f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 49 89 ca b8 af 01 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d da 32 0f 00 f7 d8 64 89 01 48 [95553.725188] RSP: 002b:00007ffe97148978 EFLAGS: 00000246 ORIG_RAX: 00000000000001af [95553.725892] RAX: ffffffffffffffda RBX: 00005dcfe53d0080 RCX: 000072ee774f3afe [95553.726526] RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000003 [95553.727176] RBP: 00007ffe97148ac0 R08: 0000000000000000 R09: 000072ee775e7ac0 [95553.727818] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 [95553.728459] R13: 00005dcfe53d04b0 R14: 000072ee77670b00 R15: 00005dcfe53d1a28 [95553.729086] </TASK>

The panic occurs as follows: 1. logical_block_size is 8KiB, causing {struct super_block *sb}->s_blocksize is initialized to 0. vfat_fill_super - fat_fill_super - sb_min_blocksize - sb_set_blocksize //return 0 when size is 8KiB. 2. __bread_gfp is called with size == 0, causing folio_alloc_buffers() to compute an offset equal to folio_size(folio), which triggers a BUG_ON. fat_fill_super - sb_bread - __bread_gfp // size == {struct super_block *sb}->s_blocksize == 0 - bdev_getblk - __getblk_slow - grow_buffers - grow_dev_folio - folio_alloc_buffers // size == 0 - folio_set_bh //offset == folio_size(folio) and panic

To fix this issue, add proper return value checks for sb_min_blocksize() in vfat, exfat, isofs, and xfs. Add the __must_check mark to sb_min_blocksize().

Cc: stable@vger.kernel.org # v6.15 Fixes: a64e5a596067bd ("bdev: add back PAGE_SIZE block size validation for sb_set_blocksize()") Signed-off-by: Yongpeng Yang yangyongpeng@xiaomi.com Reviewed-by: Matthew Wilcox willy@infradead.org Reviewed-by: Darrick J. Wong djwong@kernel.org Reviewed-by: Jan Kara jack@suse.cz Reviewed-by: OGAWA Hirofumi hirofumi@mail.parknet.co.jp --- v3: - remove the unnecessary blocksize variable definition v2: - add the __must_check mark to sb_min_blocksize() and include the Fixes tag --- block/bdev.c | 2 +- fs/exfat/super.c | 5 ++++- fs/fat/inode.c | 6 +++++- fs/isofs/inode.c | 5 +++++ fs/xfs/xfs_super.c | 5 ++++- include/linux/fs.h | 2 +- 6 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/block/bdev.c b/block/bdev.c index 810707cca970..638f0cd458ae 100644 --- a/block/bdev.c +++ b/block/bdev.c @@ -231,7 +231,7 @@ int sb_set_blocksize(struct super_block *sb, int size)

EXPORT_SYMBOL(sb_set_blocksize);

-int sb_min_blocksize(struct super_block *sb, int size) +int __must_check sb_min_blocksize(struct super_block *sb, int size) { int minsize = bdev_logical_block_size(sb->s_bdev); if (size < minsize) diff --git a/fs/exfat/super.c b/fs/exfat/super.c index 7f9592856bf7..74d451f732c7 100644 --- a/fs/exfat/super.c +++ b/fs/exfat/super.c @@ -433,7 +433,10 @@ static int exfat_read_boot_sector(struct super_block *sb) struct exfat_sb_info *sbi = EXFAT_SB(sb);

/* set block size to read super block */ - sb_min_blocksize(sb, 512); + if (!sb_min_blocksize(sb, 512)) { + exfat_err(sb, "unable to set blocksize"); + return -EINVAL; + }

/* read boot sector */ sbi->boot_bh = sb_bread(sb, 0); diff --git a/fs/fat/inode.c b/fs/fat/inode.c index 9648ed097816..9cfe20a3daaf 100644 --- a/fs/fat/inode.c +++ b/fs/fat/inode.c @@ -1595,8 +1595,12 @@ int fat_fill_super(struct super_block *sb, struct fs_context *fc,

setup(sb); /* flavour-specific stuff that needs options */

+ error = -EINVAL; + if (!sb_min_blocksize(sb, 512)) { + fat_msg(sb, KERN_ERR, "unable to set blocksize"); + goto out_fail; + } error = -EIO; - sb_min_blocksize(sb, 512); bh = sb_bread(sb, 0); if (bh == NULL) { fat_msg(sb, KERN_ERR, "unable to read boot sector"); diff --git a/fs/isofs/inode.c b/fs/isofs/inode.c index 6f0e6b19383c..ad3143d4066b 100644 --- a/fs/isofs/inode.c +++ b/fs/isofs/inode.c @@ -610,6 +610,11 @@ static int isofs_fill_super(struct super_block *s, struct fs_context *fc) goto out_freesbi; } opt->blocksize = sb_min_blocksize(s, opt->blocksize); + if (!opt->blocksize) { + printk(KERN_ERR + "ISOFS: unable to set blocksize\n"); + goto out_freesbi; + }

sbi->s_high_sierra = 0; /* default is iso9660 */ sbi->s_session = opt->session; diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c index 1067ebb3b001..bc71aa9dcee8 100644 --- a/fs/xfs/xfs_super.c +++ b/fs/xfs/xfs_super.c @@ -1693,7 +1693,10 @@ xfs_fs_fill_super( if (error) return error;

- sb_min_blocksize(sb, BBSIZE); + if (!sb_min_blocksize(sb, BBSIZE)) { + xfs_err(mp, "unable to set blocksize"); + return -EINVAL; + } sb->s_xattr = xfs_xattr_handlers; sb->s_export_op = &xfs_export_operations; #ifdef CONFIG_XFS_QUOTA diff --git a/include/linux/fs.h b/include/linux/fs.h index c895146c1444..26d4ca0f859a 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3424,7 +3424,7 @@ extern void inode_sb_list_add(struct inode *inode); extern void inode_add_lru(struct inode *inode);

extern int sb_set_blocksize(struct super_block *, int); -extern int sb_min_blocksize(struct super_block *, int); +extern int __must_check sb_min_blocksize(struct super_block *, int);

int generic_file_mmap(struct file *, struct vm_area_struct *); int generic_file_mmap_prepare(struct vm_area_desc *desc);