From 892e1cf17555735e9d021ab036c36bc7b58b0e3b Mon Sep 17 00:00:00 2001 From: Deepanshu Kartikey Date: Mon, 20 Oct 2025 11:39:36 +0530 Subject: ext4: refresh inline data size before write operations The cached ei->i_inline_size can become stale between the initial size check and when ext4_update_inline_data()/ext4_create_inline_data() use it. Although ext4_get_max_inline_size() reads the correct value at the time of the check, concurrent xattr operations can modify i_inline_size before ext4_write_lock_xattr() is acquired. This causes ext4_update_inline_data() and ext4_create_inline_data() to work with stale capacity values, leading to a BUG_ON() crash in ext4_write_inline_data(): kernel BUG at fs/ext4/inline.c:1331! BUG_ON(pos + len > EXT4_I(inode)->i_inline_size); The race window: 1. ext4_get_max_inline_size() reads i_inline_size = 60 (correct) 2. Size check passes for 50-byte write 3. [Another thread adds xattr, i_inline_size changes to 40] 4. ext4_write_lock_xattr() acquires lock 5. ext4_update_inline_data() uses stale i_inline_size = 60 6. Attempts to write 50 bytes but only 40 bytes actually available 7. BUG_ON() triggers Fix this by recalculating i_inline_size via ext4_find_inline_data_nolock() immediately after acquiring xattr_sem. This ensures ext4_update_inline_data() and ext4_create_inline_data() work with current values that are protected from concurrent modifications. This is similar to commit a54c4613dac1 ("ext4: fix race writing to an inline_data file while its xattrs are changing") which fixed i_inline_off staleness. This patch addresses the related i_inline_size staleness issue. Reported-by: syzbot+f3185be57d7e8dda32b8@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=f3185be57d7e8dda32b8 Cc: stable@kernel.org Signed-off-by: Deepanshu Kartikey Message-ID: <20251020060936.474314-1-kartikey406@gmail.com> Signed-off-by: Theodore Ts'o --- fs/ext4/inline.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'fs/ext4/inline.c') diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c index 1b094a4f3866..b48c7dbe76a2 100644 --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -418,7 +418,12 @@ static int ext4_prepare_inline_data(handle_t *handle, struct inode *inode, return -ENOSPC; ext4_write_lock_xattr(inode, &no_expand); - + /* + * ei->i_inline_size may have changed since the initial check + * if other xattrs were added. Recalculate to ensure + * ext4_update_inline_data() validates against current capacity. + */ + (void) ext4_find_inline_data_nolock(inode); if (ei->i_inline_off) ret = ext4_update_inline_data(handle, inode, len); else -- cgit From 0cd8feea8777f8d9b9a862b89c688b049a5c8475 Mon Sep 17 00:00:00 2001 From: Alexey Nepomnyashih Date: Tue, 4 Nov 2025 09:33:25 +0000 Subject: ext4: add i_data_sem protection in ext4_destroy_inline_data_nolock() Fix a race between inline data destruction and block mapping. The function ext4_destroy_inline_data_nolock() changes the inode data layout by clearing EXT4_INODE_INLINE_DATA and setting EXT4_INODE_EXTENTS. At the same time, another thread may execute ext4_map_blocks(), which tests EXT4_INODE_EXTENTS to decide whether to call ext4_ext_map_blocks() or ext4_ind_map_blocks(). Without i_data_sem protection, ext4_ind_map_blocks() may receive inode with EXT4_INODE_EXTENTS flag and triggering assert. kernel BUG at fs/ext4/indirect.c:546! EXT4-fs (loop2): unmounting filesystem. invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 RIP: 0010:ext4_ind_map_blocks.cold+0x2b/0x5a fs/ext4/indirect.c:546 Call Trace: ext4_map_blocks+0xb9b/0x16f0 fs/ext4/inode.c:681 _ext4_get_block+0x242/0x590 fs/ext4/inode.c:822 ext4_block_write_begin+0x48b/0x12c0 fs/ext4/inode.c:1124 ext4_write_begin+0x598/0xef0 fs/ext4/inode.c:1255 ext4_da_write_begin+0x21e/0x9c0 fs/ext4/inode.c:3000 generic_perform_write+0x259/0x5d0 mm/filemap.c:3846 ext4_buffered_write_iter+0x15b/0x470 fs/ext4/file.c:285 ext4_file_write_iter+0x8e0/0x17f0 fs/ext4/file.c:679 call_write_iter include/linux/fs.h:2271 [inline] do_iter_readv_writev+0x212/0x3c0 fs/read_write.c:735 do_iter_write+0x186/0x710 fs/read_write.c:861 vfs_iter_write+0x70/0xa0 fs/read_write.c:902 iter_file_splice_write+0x73b/0xc90 fs/splice.c:685 do_splice_from fs/splice.c:763 [inline] direct_splice_actor+0x10f/0x170 fs/splice.c:950 splice_direct_to_actor+0x33a/0xa10 fs/splice.c:896 do_splice_direct+0x1a9/0x280 fs/splice.c:1002 do_sendfile+0xb13/0x12c0 fs/read_write.c:1255 __do_sys_sendfile64 fs/read_write.c:1323 [inline] __se_sys_sendfile64 fs/read_write.c:1309 [inline] __x64_sys_sendfile64+0x1cf/0x210 fs/read_write.c:1309 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x6e/0xd8 Fixes: c755e251357a ("ext4: fix deadlock between inline_data and ext4_expand_extra_isize_ea()") Cc: stable@vger.kernel.org # v4.11+ Signed-off-by: Alexey Nepomnyashih Message-ID: <20251104093326.697381-1-sdl@nppct.ru> Signed-off-by: Theodore Ts'o --- fs/ext4/inline.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'fs/ext4/inline.c') diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c index b48c7dbe76a2..1f6bc05593df 100644 --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -451,9 +451,13 @@ static int ext4_destroy_inline_data_nolock(handle_t *handle, if (!ei->i_inline_off) return 0; + down_write(&ei->i_data_sem); + error = ext4_get_inode_loc(inode, &is.iloc); - if (error) + if (error) { + up_write(&ei->i_data_sem); return error; + } error = ext4_xattr_ibody_find(inode, &i, &is); if (error) @@ -492,6 +496,7 @@ out: brelse(is.iloc.bh); if (error == -ENODATA) error = 0; + up_write(&ei->i_data_sem); return error; } -- cgit