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Message-Id: <20250415-ext4-prepare-inline-overflow-v1-1-f4c13d900967@igalia.com>
Date: Tue, 15 Apr 2025 11:53:04 -0300
From: Thadeu Lima de Souza Cascardo <cascardo@...lia.com>
To: Theodore Ts'o <tytso@....edu>,
Andreas Dilger <adilger.kernel@...ger.ca>, Tao Ma <boyu.mt@...bao.com>,
Jan Kara <jack@...e.com>
Cc: linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, kernel-dev@...lia.com,
syzbot+fe2a25dae02a207717a0@...kaller.appspotmail.com,
Thadeu Lima de Souza Cascardo <cascardo@...lia.com>, stable@...r.kernel.org
Subject: [PATCH] ext4: inline: fix len overflow in ext4_prepare_inline_data
When running the following code on an ext4 filesystem with inline_data
feature enabled, it will lead to the bug below.
fd = open("file1", O_RDWR | O_CREAT | O_TRUNC, 0666);
ftruncate(fd, 30);
pwrite(fd, "a", 1, (1UL << 40) + 5UL);
That happens because write_begin will succeed as when
ext4_generic_write_inline_data calls ext4_prepare_inline_data, pos + len
will be truncated, leading to ext4_prepare_inline_data parameter to be 6
instead of 0x10000000006.
Then, later when write_end is called, we hit:
BUG_ON(pos + len > EXT4_I(inode)->i_inline_size);
at ext4_write_inline_data.
Fix it by using a loff_t type for the len parameter in
ext4_prepare_inline_data instead of an unsigned int.
[ 44.545164] ------------[ cut here ]------------
[ 44.545530] kernel BUG at fs/ext4/inline.c:240!
[ 44.545834] Oops: invalid opcode: 0000 [#1] SMP NOPTI
[ 44.546172] CPU: 3 UID: 0 PID: 343 Comm: test Not tainted 6.15.0-rc2-00003-g9080916f4863 #45 PREEMPT(full) 112853fcebfdb93254270a7959841d2c6aa2c8bb
[ 44.546523] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[ 44.546523] RIP: 0010:ext4_write_inline_data+0xfe/0x100
[ 44.546523] Code: 3c 0e 48 83 c7 48 48 89 de 5b 41 5c 41 5d 41 5e 41 5f 5d e9 e4 fa 43 01 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 0f 0b <0f> 0b 0f 1f 44 00 00 55 41 57 41 56 41 55 41 54 53 48 83 ec 20 49
[ 44.546523] RSP: 0018:ffffb342008b79a8 EFLAGS: 00010216
[ 44.546523] RAX: 0000000000000001 RBX: ffff9329c579c000 RCX: 0000010000000006
[ 44.546523] RDX: 000000000000003c RSI: ffffb342008b79f0 RDI: ffff9329c158e738
[ 44.546523] RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000
[ 44.546523] R10: 00007ffffffff000 R11: ffffffff9bd0d910 R12: 0000006210000000
[ 44.546523] R13: fffffc7e4015e700 R14: 0000010000000005 R15: ffff9329c158e738
[ 44.546523] FS: 00007f4299934740(0000) GS:ffff932a60179000(0000) knlGS:0000000000000000
[ 44.546523] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 44.546523] CR2: 00007f4299a1ec90 CR3: 0000000002886002 CR4: 0000000000770eb0
[ 44.546523] PKRU: 55555554
[ 44.546523] Call Trace:
[ 44.546523] <TASK>
[ 44.546523] ext4_write_inline_data_end+0x126/0x2d0
[ 44.546523] generic_perform_write+0x17e/0x270
[ 44.546523] ext4_buffered_write_iter+0xc8/0x170
[ 44.546523] vfs_write+0x2be/0x3e0
[ 44.546523] __x64_sys_pwrite64+0x6d/0xc0
[ 44.546523] do_syscall_64+0x6a/0xf0
[ 44.546523] ? __wake_up+0x89/0xb0
[ 44.546523] ? xas_find+0x72/0x1c0
[ 44.546523] ? next_uptodate_folio+0x317/0x330
[ 44.546523] ? set_pte_range+0x1a6/0x270
[ 44.546523] ? filemap_map_pages+0x6ee/0x840
[ 44.546523] ? ext4_setattr+0x2fa/0x750
[ 44.546523] ? do_pte_missing+0x128/0xf70
[ 44.546523] ? security_inode_post_setattr+0x3e/0xd0
[ 44.546523] ? ___pte_offset_map+0x19/0x100
[ 44.546523] ? handle_mm_fault+0x721/0xa10
[ 44.546523] ? do_user_addr_fault+0x197/0x730
[ 44.546523] ? do_syscall_64+0x76/0xf0
[ 44.546523] ? arch_exit_to_user_mode_prepare+0x1e/0x60
[ 44.546523] ? irqentry_exit_to_user_mode+0x79/0x90
[ 44.546523] entry_SYSCALL_64_after_hwframe+0x55/0x5d
[ 44.546523] RIP: 0033:0x7f42999c6687
[ 44.546523] Code: 48 89 fa 4c 89 df e8 58 b3 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
[ 44.546523] RSP: 002b:00007ffeae4a7930 EFLAGS: 00000202 ORIG_RAX: 0000000000000012
[ 44.546523] RAX: ffffffffffffffda RBX: 00007f4299934740 RCX: 00007f42999c6687
[ 44.546523] RDX: 0000000000000001 RSI: 000055ea6149200f RDI: 0000000000000003
[ 44.546523] RBP: 00007ffeae4a79a0 R08: 0000000000000000 R09: 0000000000000000
[ 44.546523] R10: 0000010000000005 R11: 0000000000000202 R12: 0000000000000000
[ 44.546523] R13: 00007ffeae4a7ac8 R14: 00007f4299b86000 R15: 000055ea61493dd8
[ 44.546523] </TASK>
[ 44.546523] Modules linked in:
[ 44.568501] ---[ end trace 0000000000000000 ]---
[ 44.568889] RIP: 0010:ext4_write_inline_data+0xfe/0x100
[ 44.569328] Code: 3c 0e 48 83 c7 48 48 89 de 5b 41 5c 41 5d 41 5e 41 5f 5d e9 e4 fa 43 01 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 0f 0b <0f> 0b 0f 1f 44 00 00 55 41 57 41 56 41 55 41 54 53 48 83 ec 20 49
[ 44.570931] RSP: 0018:ffffb342008b79a8 EFLAGS: 00010216
[ 44.571356] RAX: 0000000000000001 RBX: ffff9329c579c000 RCX: 0000010000000006
[ 44.571959] RDX: 000000000000003c RSI: ffffb342008b79f0 RDI: ffff9329c158e738
[ 44.572571] RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000
[ 44.573148] R10: 00007ffffffff000 R11: ffffffff9bd0d910 R12: 0000006210000000
[ 44.573748] R13: fffffc7e4015e700 R14: 0000010000000005 R15: ffff9329c158e738
[ 44.574335] FS: 00007f4299934740(0000) GS:ffff932a60179000(0000) knlGS:0000000000000000
[ 44.575027] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 44.575520] CR2: 00007f4299a1ec90 CR3: 0000000002886002 CR4: 0000000000770eb0
[ 44.576112] PKRU: 55555554
[ 44.576338] Kernel panic - not syncing: Fatal exception
[ 44.576517] Kernel Offset: 0x1a600000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
Reported-by: syzbot+fe2a25dae02a207717a0@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=fe2a25dae02a207717a0
Fixes: f19d5870cbf7 ("ext4: add normal write support for inline data")
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@...lia.com>
Cc: stable@...r.kernel.org
---
fs/ext4/inline.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index 2c9b762925c72f2ff5a402b02500370bc1eb0eb1..e5e6bf0d338b965a885fb99581f9ed5e51c5257c 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -397,7 +397,7 @@ static int ext4_update_inline_data(handle_t *handle, struct inode *inode,
}
static int ext4_prepare_inline_data(handle_t *handle, struct inode *inode,
- unsigned int len)
+ loff_t len)
{
int ret, size, no_expand;
struct ext4_inode_info *ei = EXT4_I(inode);
---
base-commit: 8ffd015db85fea3e15a77027fda6c02ced4d2444
change-id: 20250415-ext4-prepare-inline-overflow-8db0e747cb16
Best regards,
--
Thadeu Lima de Souza Cascardo <cascardo@...lia.com>
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