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Darrick J. Wong c5d7c31e17 ext4: fix another off-by-one fsmap error on 1k block filesystems 
commit c993799baf upstream.

Apparently syzbot figured out that issuing this FSMAP call:

struct fsmap_head cmd = {
	.fmh_count	= ...;
	.fmh_keys	= {
		{ .fmr_device = /* ext4 dev */, .fmr_physical = 0, },
		{ .fmr_device = /* ext4 dev */, .fmr_physical = 0, },
	},
...
};
ret = ioctl(fd, FS_IOC_GETFSMAP, &cmd);

Produces this crash if the underlying filesystem is a 1k-block ext4
filesystem:

kernel BUG at fs/ext4/ext4.h:3331!
invalid opcode: 0000 [#1] PREEMPT SMP
CPU: 3 PID: 3227965 Comm: xfs_io Tainted: G        W  O       6.2.0-rc8-achx
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014
RIP: 0010:ext4_mb_load_buddy_gfp+0x47c/0x570 [ext4]
RSP: 0018:ffffc90007c03998 EFLAGS: 00010246
RAX: ffff888004978000 RBX: ffffc90007c03a20 RCX: ffff888041618000
RDX: 0000000000000000 RSI: 00000000000005a4 RDI: ffffffffa0c99b11
RBP: ffff888012330000 R08: ffffffffa0c2b7d0 R09: 0000000000000400
R10: ffffc90007c03950 R11: 0000000000000000 R12: 0000000000000001
R13: 00000000ffffffff R14: 0000000000000c40 R15: ffff88802678c398
FS:  00007fdf2020c880(0000) GS:ffff88807e100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd318a5fe8 CR3: 000000007f80f001 CR4: 00000000001706e0
Call Trace:
 <TASK>
 ext4_mballoc_query_range+0x4b/0x210 [ext4 dfa189daddffe8fecd3cdfd00564e0f265a8ab80]
 ext4_getfsmap_datadev+0x713/0x890 [ext4 dfa189daddffe8fecd3cdfd00564e0f265a8ab80]
 ext4_getfsmap+0x2b7/0x330 [ext4 dfa189daddffe8fecd3cdfd00564e0f265a8ab80]
 ext4_ioc_getfsmap+0x153/0x2b0 [ext4 dfa189daddffe8fecd3cdfd00564e0f265a8ab80]
 __ext4_ioctl+0x2a7/0x17e0 [ext4 dfa189daddffe8fecd3cdfd00564e0f265a8ab80]
 __x64_sys_ioctl+0x82/0xa0
 do_syscall_64+0x2b/0x80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0
RIP: 0033:0x7fdf20558aff
RSP: 002b:00007ffd318a9e30 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000000200c0 RCX: 00007fdf20558aff
RDX: 00007fdf1feb2010 RSI: 00000000c0c0583b RDI: 0000000000000003
RBP: 00005625c0634be0 R08: 00005625c0634c40 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdf1feb2010
R13: 00005625be70d994 R14: 0000000000000800 R15: 0000000000000000

For GETFSMAP calls, the caller selects a physical block device by
writing its block number into fsmap_head.fmh_keys[01].fmr_device.
To query mappings for a subrange of the device, the starting byte of the
range is written to fsmap_head.fmh_keys[0].fmr_physical and the last
byte of the range goes in fsmap_head.fmh_keys[1].fmr_physical.

IOWs, to query what mappings overlap with bytes 3-14 of /dev/sda, you'd
set the inputs as follows:

	fmh_keys[0] = { .fmr_device = major(8, 0), .fmr_physical = 3},
	fmh_keys[1] = { .fmr_device = major(8, 0), .fmr_physical = 14},

Which would return you whatever is mapped in the 12 bytes starting at
physical offset 3.

The crash is due to insufficient range validation of keys[1] in
ext4_getfsmap_datadev.  On 1k-block filesystems, block 0 is not part of
the filesystem, which means that s_first_data_block is nonzero.
ext4_get_group_no_and_offset subtracts this quantity from the blocknr
argument before cracking it into a group number and a block number
within a group.  IOWs, block group 0 spans blocks 1-8192 (1-based)
instead of 0-8191 (0-based) like what happens with larger blocksizes.

The net result of this encoding is that blocknr < s_first_data_block is
not a valid input to this function.  The end_fsb variable is set from
the keys that are copied from userspace, which means that in the above
example, its value is zero.  That leads to an underflow here:

	blocknr = blocknr - le32_to_cpu(es->s_first_data_block);

The division then operates on -1:

	offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) >>
		EXT4_SB(sb)->s_cluster_bits;

Leaving an impossibly large group number (2^32-1) in blocknr.
ext4_getfsmap_check_keys checked that keys[0].fmr_physical and
keys[1].fmr_physical are in increasing order, but
ext4_getfsmap_datadev adjusts keys[0].fmr_physical to be at least
s_first_data_block.  This implies that we have to check it again after
the adjustment, which is the piece that I forgot.

Reported-by: syzbot+6be2b977c89f79b6b153@syzkaller.appspotmail.com
Fixes: 4a4956249d ("ext4: fix off-by-one fsmap error on 1k block filesystems")
Link: https://syzkaller.appspot.com/bug?id=79d5768e9bfe362911ac1a5057a36fc6b5c30002
Cc: stable@vger.kernel.org
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/Y+58NPTH7VNGgzdd@magnolia
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-03-17 08:48:48 +01:00
arch x86/CPU/AMD: Disable XSAVES on AMD family 0x17 2023-03-17 08:48:47 +01:00
block block: don't allow multiple bios for IOCB_NOWAIT issue 2023-03-10 09:39:55 +01:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto crypto: rsa-pkcs1pad - Use akcipher_request_complete 2023-03-10 09:39:16 +01:00
Documentation usb: gadget: uvc: Make bSourceID read/write 2023-03-11 13:57:37 +01:00
drivers staging: rtl8723bs: Pass correct parameters to cfg80211_get_bss() 2023-03-17 08:48:48 +01:00
fs ext4: fix another off-by-one fsmap error on 1k block filesystems 2023-03-17 08:48:48 +01:00
include PCI: Add ACS quirk for Wangxun NICs 2023-03-11 13:57:38 +01:00
init kbuild: Add CONFIG_PAHOLE_VERSION 2023-02-25 12:06:45 +01:00
io_uring io_uring/poll: allow some retries for poll triggering spuriously 2023-03-10 09:40:04 +01:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:28:45 +01:00
kernel fork: allow CLONE_NEWTIME in clone3 flags 2023-03-17 08:48:47 +01:00
lib kobject: Fix slab-out-of-bounds in fill_kobj_path() 2023-03-10 09:39:35 +01:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm/thp: check and bail out if page in deferred queue already 2023-03-10 09:40:09 +01:00
net wifi: cfg80211: Partial revert "wifi: cfg80211: Fix use after free for wext" 2023-03-13 10:20:37 +01:00
samples samples: vfio-mdev: Fix missing pci_disable_device() in mdpy_fb_probe() 2022-12-31 13:14:31 +01:00
scripts builddeb: clean generated package content 2023-03-10 09:39:44 +01:00
security ima: Align ima_file_mmap() parameters with mmap_file LSM hook 2023-03-10 09:40:03 +01:00
sound ASoC: mediatek: mt8195: add missing initialization 2023-03-11 13:57:32 +01:00
tools perf inject: Fix --buildid-all not to eat up MMAP2 2023-03-17 08:48:47 +01:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt KVM: Destroy target device if coalesced MMIO unregistration fails 2023-03-10 09:40:00 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild
Kconfig
MAINTAINERS kbuild: Add CONFIG_PAHOLE_VERSION 2023-02-25 12:06:45 +01:00
Makefile Linux 5.15.102 2023-03-13 10:20:37 +01:00
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