Hi Ye Bin, Greetings! I used Syzkaller and found that there is kernel BUG in ext4_update_inline_data in linux v6.15-rc2. After bisection and the first bad commit is: " 5701875f9609 ext4: fix out-of-bound read in ext4_xattr_inode_dec_ref_all() " All detailed into can be found at: https://github.com/laifryiee/syzkaller_logs/tree/main/250416_221056_ext4_update_inline_data Syzkaller repro code: https://github.com/laifryiee/syzkaller_logs/tree/main/250416_221056_ext4_update_inline_data/repro.c Syzkaller repro syscall steps: https://github.com/laifryiee/syzkaller_logs/tree/main/250416_221056_ext4_update_inline_data/repro.prog Syzkaller report: https://github.com/laifryiee/syzkaller_logs/tree/main/250416_221056_ext4_update_inline_data/repro.report Kconfig(make olddefconfig): https://github.com/laifryiee/syzkaller_logs/tree/main/250416_221056_ext4_update_inline_data/kconfig_origin Bisect info: https://github.com/laifryiee/syzkaller_logs/tree/main/250416_221056_ext4_update_inline_data/bisect_info.log bzImage: https://github.com/laifryiee/syzkaller_logs/raw/refs/heads/main/250416_221056_ext4_update_inline_data/bzImage_5701875f9609b000d91351eaa6bfd97fe2f157f4 Issue dmesg: https://github.com/laifryiee/syzkaller_logs/blob/main/250416_221056_ext4_update_inline_data/5701875f9609b000d91351eaa6bfd97fe2f157f4_dmesg.log " [ 21.479561] ------------[ cut here ]------------ [ 21.480014] kernel BUG at fs/ext4/inline.c:357! [ 21.480408] Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI [ 21.480918] CPU: 1 UID: 0 PID: 718 Comm: repro Tainted: G W 6.14.0-rc2-5701875f9609+ #1 [ 21.481634] Tainted: [W]=WARN [ 21.481882] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebui4 [ 21.482739] RIP: 0010:ext4_update_inline_data+0x48c/0x500 [ 21.483193] Code: 0f 84 cc fc ff ff e8 c3 c0 50 ff 4c 89 e7 e8 bb 80 db ff e9 ba fc ff ff 48 89 cf e8 3e f [ 21.484587] RSP: 0018:ff11000011637678 EFLAGS: 00010293 [ 21.485002] RAX: 0000000000000000 RBX: 1fe22000022c6ed5 RCX: ffffffff82372a1f [ 21.485547] RDX: ff110000168dabc0 RSI: ffffffff82372cac RDI: 0000000000000005 [ 21.486094] RBP: ff110000116377b0 R08: ffffffff85e27b00 R09: 0000000000000000 [ 21.486640] R10: 00000000ffffffc3 R11: 1ffffffff11f3787 R12: ff1100001d937910 [ 21.487312] R13: 000000000000080c R14: 00000000ffffffc3 R15: ff11000011637788 [ 21.487867] FS: 00007f9610273740(0000) GS:ff1100006c900000(0000) knlGS:0000000000000000 [ 21.488481] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.488931] CR2: 00007fffee66eed8 CR3: 0000000018d60004 CR4: 0000000000771ef0 [ 21.489479] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 21.490027] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400 [ 21.490570] PKRU: 55555554 [ 21.491092] Call Trace: [ 21.491310] <TASK> [ 21.491493] ? show_regs+0x6d/0x80 [ 21.491780] ? die+0x3c/0xa0 [ 21.492044] ? do_trap+0x230/0x410 [ 21.492332] ? do_error_trap+0xf2/0x210 [ 21.492644] ? ext4_update_inline_data+0x48c/0x500 [ 21.493038] ? handle_invalid_op+0x39/0x50 [ 21.493370] ? ext4_update_inline_data+0x48c/0x500 [ 21.493758] ? exc_invalid_op+0x63/0x80 [ 21.494073] ? asm_exc_invalid_op+0x1f/0x30 [ 21.494417] ? ext4_update_inline_data+0x1ff/0x500 [ 21.495074] ? ext4_update_inline_data+0x48c/0x500 [ 21.495492] ? ext4_update_inline_data+0x48c/0x500 [ 21.495902] ? ext4_update_inline_data+0x48c/0x500 [ 21.496293] ? __pfx_ext4_update_inline_data+0x10/0x10 [ 21.496713] ? __sanitizer_cov_trace_const_cmp2+0x1c/0x30 [ 21.497145] ? ext4_journal_check_start+0x23f/0x360 [ 21.497538] ext4_prepare_inline_data+0x1fa/0x260 [ 21.497926] ext4_generic_write_inline_data+0x1d5/0xaf0 [ 21.498340] ? __pfx_ext4_generic_write_inline_data+0x10/0x10 [ 21.499087] ? __this_cpu_preempt_check+0x21/0x30 [ 21.499494] ext4_da_write_begin+0x713/0x920 [ 21.499866] ? __sanitizer_cov_trace_cmp8+0x1c/0x30 [ 21.500262] ? __pfx_ext4_da_write_begin+0x10/0x10 [ 21.500649] ? balance_dirty_pages_ratelimited_flags+0x9b/0x12a0 [ 21.501129] ? fault_in_iov_iter_readable+0x78/0x2e0 [ 21.501530] generic_perform_write+0x2f8/0x8f0 [ 21.501904] ? __pfx_generic_perform_write+0x10/0x10 [ 21.502316] ? __sanitizer_cov_trace_const_cmp4+0x1a/0x20 [ 21.502796] ? mnt_put_write_access_file+0x5c/0x110 [ 21.503193] ext4_buffered_write_iter+0x127/0x460 [ 21.503572] ext4_file_write_iter+0xb32/0x1ee0 [ 21.503939] ? lock_acquire+0x1cd/0x550 [ 21.504253] ? __pfx_ext4_file_write_iter+0x10/0x10 [ 21.504642] ? __this_cpu_preempt_check+0x21/0x30 [ 21.505018] ? lock_is_held_type+0xef/0x150 [ 21.505360] vfs_write+0xc60/0x1140 [ 21.505651] ? __pfx_ext4_file_write_iter+0x10/0x10 [ 21.506044] ? __pfx_vfs_write+0x10/0x10 [ 21.506373] ? __sanitizer_cov_trace_const_cmp8+0x1c/0x30 [ 21.507075] ksys_write+0x14f/0x280 [ 21.507360] ? __pfx_ksys_write+0x10/0x10 [ 21.507700] __x64_sys_write+0x7b/0xc0 [ 21.508033] x64_sys_call+0x16b3/0x2140 [ 21.508349] do_syscall_64+0x6d/0x140 [ 21.508652] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 21.509059] RIP: 0033:0x7f961003ee5d [ 21.509348] Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 8 [ 21.511028] RSP: 002b:00007fff627878b8 EFLAGS: 00000287 ORIG_RAX: 0000000000000001 [ 21.511634] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f961003ee5d [ 21.512201] RDX: 000000000000080c RSI: 0000200000001700 RDI: 0000000000000004 [ 21.512751] RBP: 00007fff627878d0 R08: 0000000000000010 R09: 0000000000000010 [ 21.513302] R10: 0000000000000000 R11: 0000000000000287 R12: 00007fff62787a48 [ 21.513852] R13: 0000000000403757 R14: 0000000000406e08 R15: 00007f96102be000 [ 21.514411] </TASK> [ 21.514596] Modules linked in: [ 21.515293] ---[ end trace 0000000000000000 ]--- " Hope this cound be insightful to you. Regards, Yi Lai --- If you don't need the following environment to reproduce the problem or if you already have one reproduced environment, please ignore the following information. How to reproduce: git clone https://gitlab.com/xupengfe/repro_vm_env.git cd repro_vm_env tar -xvf repro_vm_env.tar.gz cd repro_vm_env; ./start3.sh // it needs qemu-system-x86_64 and I used v7.1.0 // start3.sh will load bzImage_2241ab53cbb5cdb08a6b2d4688feb13971058f65 v6.2-rc5 kernel // You could change the bzImage_xxx as you want // Maybe you need to remove line "-drive if=pflash,format=raw,readonly=on,file=./OVMF_CODE.fd \" for different qemu version You could use below command to log in, there is no password for root. ssh -p 10023 root@localhost After login vm(virtual machine) successfully, you could transfer reproduced binary to the vm by below way, and reproduce the problem in vm: gcc -pthread -o repro repro.c scp -P 10023 repro root@localhost:/root/ Get the bzImage for target kernel: Please use target kconfig and copy it to kernel_src/.config make olddefconfig make -jx bzImage //x should equal or less than cpu num your pc has Fill the bzImage file into above start3.sh to load the target kernel in vm. Tips: If you already have qemu-system-x86_64, please ignore below info. If you want to install qemu v7.1.0 version: git clone https://github.com/qemu/qemu.git cd qemu git checkout -f v7.1.0 mkdir build cd build yum install -y ninja-build.x86_64 yum -y install libslirp-devel.x86_64 ../configure --target-list=x86_64-softmmu --enable-kvm --enable-vnc --enable-gtk --enable-sdl --enable-usb-redir --enable-slirp make make install On Sat, Feb 08, 2025 at 02:31:41PM +0800, Ye Bin wrote: > From: Ye Bin <yebin10@xxxxxxxxxx> > > There's issue as follows: > BUG: KASAN: use-after-free in ext4_xattr_inode_dec_ref_all+0x6ff/0x790 > Read of size 4 at addr ffff88807b003000 by task syz-executor.0/15172 > > CPU: 3 PID: 15172 Comm: syz-executor.0 > Call Trace: > __dump_stack lib/dump_stack.c:82 [inline] > dump_stack+0xbe/0xfd lib/dump_stack.c:123 > print_address_description.constprop.0+0x1e/0x280 mm/kasan/report.c:400 > __kasan_report.cold+0x6c/0x84 mm/kasan/report.c:560 > kasan_report+0x3a/0x50 mm/kasan/report.c:585 > ext4_xattr_inode_dec_ref_all+0x6ff/0x790 fs/ext4/xattr.c:1137 > ext4_xattr_delete_inode+0x4c7/0xda0 fs/ext4/xattr.c:2896 > ext4_evict_inode+0xb3b/0x1670 fs/ext4/inode.c:323 > evict+0x39f/0x880 fs/inode.c:622 > iput_final fs/inode.c:1746 [inline] > iput fs/inode.c:1772 [inline] > iput+0x525/0x6c0 fs/inode.c:1758 > ext4_orphan_cleanup fs/ext4/super.c:3298 [inline] > ext4_fill_super+0x8c57/0xba40 fs/ext4/super.c:5300 > mount_bdev+0x355/0x410 fs/super.c:1446 > legacy_get_tree+0xfe/0x220 fs/fs_context.c:611 > vfs_get_tree+0x8d/0x2f0 fs/super.c:1576 > do_new_mount fs/namespace.c:2983 [inline] > path_mount+0x119a/0x1ad0 fs/namespace.c:3316 > do_mount+0xfc/0x110 fs/namespace.c:3329 > __do_sys_mount fs/namespace.c:3540 [inline] > __se_sys_mount+0x219/0x2e0 fs/namespace.c:3514 > do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46 > entry_SYSCALL_64_after_hwframe+0x67/0xd1 > > Memory state around the buggy address: > ffff88807b002f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > ffff88807b002f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > >ffff88807b003000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ^ > ffff88807b003080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ffff88807b003100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > > Above issue happens as ext4_xattr_delete_inode() isn't check xattr > is valid if xattr is in inode. > To solve above issue call xattr_check_inode() check if xattr if valid > in inode. In fact, we can directly verify in ext4_iget_extra_inode(), > so that there is no divergent verification. > > Fixes: e50e5129f384 ("ext4: xattr-in-inode support") > Signed-off-by: Ye Bin <yebin10@xxxxxxxxxx> > --- > fs/ext4/inode.c | 5 +++++ > fs/ext4/xattr.c | 26 +------------------------- > fs/ext4/xattr.h | 7 +++++++ > 3 files changed, 13 insertions(+), 25 deletions(-) > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 7c54ae5fcbd4..af735386aa44 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -4674,6 +4674,11 @@ static inline int ext4_iget_extra_inode(struct inode *inode, > *magic == cpu_to_le32(EXT4_XATTR_MAGIC)) { > int err; > > + err = xattr_check_inode(inode, IHDR(inode, raw_inode), > + ITAIL(inode, raw_inode)); > + if (err) > + return err; > + > ext4_set_inode_state(inode, EXT4_STATE_XATTR); > err = ext4_find_inline_data_nolock(inode); > if (!err && ext4_has_inline_data(inode)) > diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c > index 0e4494863d15..a10fb8a9d02d 100644 > --- a/fs/ext4/xattr.c > +++ b/fs/ext4/xattr.c > @@ -308,7 +308,7 @@ __ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh, > __ext4_xattr_check_block((inode), (bh), __func__, __LINE__) > > > -static inline int > +int > __xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header, > void *end, const char *function, unsigned int line) > { > @@ -316,9 +316,6 @@ __xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header, > function, line); > } > > -#define xattr_check_inode(inode, header, end) \ > - __xattr_check_inode((inode), (header), (end), __func__, __LINE__) > - > static int > xattr_find_entry(struct inode *inode, struct ext4_xattr_entry **pentry, > void *end, int name_index, const char *name, int sorted) > @@ -650,9 +647,6 @@ ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name, > raw_inode = ext4_raw_inode(&iloc); > header = IHDR(inode, raw_inode); > end = ITAIL(inode, raw_inode); > - error = xattr_check_inode(inode, header, end); > - if (error) > - goto cleanup; > entry = IFIRST(header); > error = xattr_find_entry(inode, &entry, end, name_index, name, 0); > if (error) > @@ -783,7 +777,6 @@ ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size) > struct ext4_xattr_ibody_header *header; > struct ext4_inode *raw_inode; > struct ext4_iloc iloc; > - void *end; > int error; > > if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR)) > @@ -793,14 +786,9 @@ ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size) > return error; > raw_inode = ext4_raw_inode(&iloc); > header = IHDR(inode, raw_inode); > - end = ITAIL(inode, raw_inode); > - error = xattr_check_inode(inode, header, end); > - if (error) > - goto cleanup; > error = ext4_xattr_list_entries(dentry, IFIRST(header), > buffer, buffer_size); > > -cleanup: > brelse(iloc.bh); > return error; > } > @@ -868,7 +856,6 @@ int ext4_get_inode_usage(struct inode *inode, qsize_t *usage) > struct ext4_xattr_ibody_header *header; > struct ext4_xattr_entry *entry; > qsize_t ea_inode_refs = 0; > - void *end; > int ret; > > lockdep_assert_held_read(&EXT4_I(inode)->xattr_sem); > @@ -879,10 +866,6 @@ int ext4_get_inode_usage(struct inode *inode, qsize_t *usage) > goto out; > raw_inode = ext4_raw_inode(&iloc); > header = IHDR(inode, raw_inode); > - end = ITAIL(inode, raw_inode); > - ret = xattr_check_inode(inode, header, end); > - if (ret) > - goto out; > > for (entry = IFIRST(header); !IS_LAST_ENTRY(entry); > entry = EXT4_XATTR_NEXT(entry)) > @@ -2237,9 +2220,6 @@ int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i, > is->s.here = is->s.first; > is->s.end = ITAIL(inode, raw_inode); > if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) { > - error = xattr_check_inode(inode, header, is->s.end); > - if (error) > - return error; > /* Find the named attribute. */ > error = xattr_find_entry(inode, &is->s.here, is->s.end, > i->name_index, i->name, 0); > @@ -2790,10 +2770,6 @@ int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize, > min_offs = end - base; > total_ino = sizeof(struct ext4_xattr_ibody_header) + sizeof(u32); > > - error = xattr_check_inode(inode, header, end); > - if (error) > - goto cleanup; > - > ifree = ext4_xattr_free_space(base, &min_offs, base, &total_ino); > if (ifree >= isize_diff) > goto shift; > diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h > index 5197f17ffd9a..1fedf44d4fb6 100644 > --- a/fs/ext4/xattr.h > +++ b/fs/ext4/xattr.h > @@ -209,6 +209,13 @@ extern int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode, > extern struct mb_cache *ext4_xattr_create_cache(void); > extern void ext4_xattr_destroy_cache(struct mb_cache *); > > +extern int > +__xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header, > + void *end, const char *function, unsigned int line); > + > +#define xattr_check_inode(inode, header, end) \ > + __xattr_check_inode((inode), (header), (end), __func__, __LINE__) > + > #ifdef CONFIG_EXT4_FS_SECURITY > extern int ext4_init_security(handle_t *handle, struct inode *inode, > struct inode *dir, const struct qstr *qstr); > -- > 2.34.1 >
