| Message ID | 20220726224428.407887-1-tadeusz.struk@linaro.org |
|---|---|
| State | Rejected |
| Headers | show |
| Series | ext4: try to flush inline data before calling BUG in writepages | expand |
On Tue 26-07-22 15:44:28, Tadeusz Struk wrote: > Fix a syzbot issue, which triggers a BUG in ext4_writepags. > The syzbot creates and monuts an ext4 fs image on /dev/loop0. > The image is corrupted, which is probably the source of the > problems, but the mount operation finishes successfully. > Then the repro program creates a file on the mounted fs, and > eventually it writes a buff of 22 zero bytes to it as below: > > memfd_create("syzkaller", 0) = 3 > ftruncate(3, 2097152) = 0 > pwrite64(3, " \0\0\0\0\2\0\0\31\0\0\0\220\1\0\0\17\0\0\0\0\0\0\0\2\0\0\0\6\0\0\0"..., 102, 1024) = 102 > pwrite64(3, "\0\0\0\0\0\0\0\0\0\0\0\0\202\343g$\306\363L\252\204n\322\345'p3x\1\0@", 31, 1248) = 31 > pwrite64(3, "\2\0\0\0\3\0\0\0\4\0\0\0\31\0\17\0\3\0\4\0\0\0\0\0\0\0\0\0\17\0.i", 32, 4096) = 32 > pwrite64(3, "\177\0\0\0\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377"..., 4098, 8192) = 4098 > pwrite64(3, "\355A\0\0\20\0\0\0\332\364e_\333\364e_\333\364e_\0\0\0\0\0\0\4\0\200\0\0\0"..., 61, 17408) = 61 > openat(AT_FDCWD, "/dev/loop0", O_RDWR) = 4 > ioctl(4, LOOP_SET_FD, 3) = 0 > mkdir("./file0", 0777) = -1 EEXIST (File exists) > mount("/dev/loop0", "./file0", "ext4", 0, ",errors=continue") = 0 > openat(AT_FDCWD, "./file0", O_RDONLY|O_DIRECTORY) = 5 > ioctl(4, LOOP_CLR_FD) = 0 > close(4) = 0 > close(3) = 0 > chdir("./file0") = 0 > creat("./bus", 000) = 3 > open("./bus", O_RDWR|O_CREAT|O_NONBLOCK|O_SYNC|O_DIRECT|O_LARGEFILE|O_NOATIME, 000) = 4 > openat(AT_FDCWD, "/proc/self/exe", O_RDONLY) = 6 > sendfile(4, 6, NULL, 2147483663) = 1638400 > open("./bus", O_RDWR|O_CREAT|O_SYNC|O_NOATIME, 000) = 7 > write(7, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 22) <unfinished ...> > > This triggers a BUG in ext4_writepages(), where it checks if > the inode has inline data, just before deleting it: Thanks for your persistence looking into this! :) I'll note that you actually miss one important call in the trace: ftruncate(3, 1) With that I can indeed reproduce the crash (after some more tweaking because for me /proc/self/exe does not have size which is multiple of 4k and so sendfile() was failing for me initially). > kernel BUG at fs/ext4/inode.c:2721! > invalid opcode: 0000 [#1] PREEMPT SMP KASAN > CPU: 0 PID: 359 Comm: repro Not tainted 5.19.0-rc8-00001-g31ba1e3b8305-dirty #15 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.fc36 04/01/2014 > RIP: 0010:ext4_writepages+0x363d/0x3660 > RSP: 0018:ffffc90000ccf260 EFLAGS: 00010293 > RAX: ffffffff81e1abcd RBX: 0000008000000000 RCX: ffff88810842a180 > RDX: 0000000000000000 RSI: 0000008000000000 RDI: 0000000000000000 > RBP: ffffc90000ccf650 R08: ffffffff81e17d58 R09: ffffed10222c680b > R10: dfffe910222c680c R11: 1ffff110222c680a R12: ffff888111634128 > R13: ffffc90000ccf880 R14: 0000008410000000 R15: 0000000000000001 > FS: 00007f72635d2640(0000) GS:ffff88811b000000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000565243379180 CR3: 000000010aa74000 CR4: 0000000000150eb0 > Call Trace: > <TASK> > do_writepages+0x397/0x640 > filemap_fdatawrite_wbc+0x151/0x1b0 > file_write_and_wait_range+0x1c9/0x2b0 > ext4_sync_file+0x19e/0xa00 > vfs_fsync_range+0x17b/0x190 > ext4_buffered_write_iter+0x488/0x530 > ext4_file_write_iter+0x449/0x1b90 > vfs_write+0xbcd/0xf40 > ksys_write+0x198/0x2c0 > __x64_sys_write+0x7b/0x90 > do_syscall_64+0x3d/0x90 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > </TASK> > > This can be prevented by forcing the inline data to be converted > and/or flushed beforehand. > This patch adds a call to ext4_convert_inline_data() just before > the BUG, which fixes the issue. This is just papering over the real problem, which is that direct IO that allocated blocks to the file did not clear EXT4_STATE_MAY_INLINE_DATA. I'll send a better fix. Honza > > Link: https://syzkaller.appspot.com/bug?id=a1e89d09bbbcbd5c4cb45db230ee28c822953984 > Reported-by: syzbot+bd13648a53ed6933ca49@syzkaller.appspotmail.com > Signed-off-by: Tadeusz Struk <tadeusz.struk@linaro.org> > --- > fs/ext4/inode.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 84c0eb55071d..de2aa2e79052 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -2717,6 +2717,10 @@ static int ext4_writepages(struct address_space *mapping, > ret = PTR_ERR(handle); > goto out_writepages; > } > + > + if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) > + WARN_ON(ext4_convert_inline_data(inode)); > + > BUG_ON(ext4_test_inode_state(inode, > EXT4_STATE_MAY_INLINE_DATA)); > ext4_destroy_inline_data(handle, inode); > -- > 2.37.1
On Tue, Jul 26, 2022 at 03:44:28PM -0700, Tadeusz Struk wrote: > Fix a syzbot issue, which triggers a BUG in ext4_writepags. > The syzbot creates and monuts an ext4 fs image on /dev/loop0. > The image is corrupted, which is probably the source of the > problems, but the mount operation finishes successfully. > Then the repro program creates a file on the mounted fs, and > eventually it writes a buff of 22 zero bytes to it as below: > > memfd_create("syzkaller", 0) = 3 > ftruncate(3, 2097152) = 0 > pwrite64(3, " \0\0\0\0\2\0\0\31\0\0\0\220\1\0\0\17\0\0\0\0\0\0\0\2\0\0\0\6\0\0\0"..., 102, 1024) = 102 > pwrite64(3, "\0\0\0\0\0\0\0\0\0\0\0\0\202\343g$\306\363L\252\204n\322\345'p3x\1\0@", 31, 1248) = 31 > pwrite64(3, "\2\0\0\0\3\0\0\0\4\0\0\0\31\0\17\0\3\0\4\0\0\0\0\0\0\0\0\0\17\0.i", 32, 4096) = 32 > pwrite64(3, "\177\0\0\0\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377"..., 4098, 8192) = 4098 > pwrite64(3, "\355A\0\0\20\0\0\0\332\364e_\333\364e_\333\364e_\0\0\0\0\0\0\4\0\200\0\0\0"..., 61, 17408) = 61 > openat(AT_FDCWD, "/dev/loop0", O_RDWR) = 4 > ioctl(4, LOOP_SET_FD, 3) = 0 > mkdir("./file0", 0777) = -1 EEXIST (File exists) > mount("/dev/loop0", "./file0", "ext4", 0, ",errors=continue") = 0 > openat(AT_FDCWD, "./file0", O_RDONLY|O_DIRECTORY) = 5 > ioctl(4, LOOP_CLR_FD) = 0 > close(4) = 0 > close(3) = 0 > chdir("./file0") = 0 > creat("./bus", 000) = 3 > open("./bus", O_RDWR|O_CREAT|O_NONBLOCK|O_SYNC|O_DIRECT|O_LARGEFILE|O_NOATIME, 000) = 4 > openat(AT_FDCWD, "/proc/self/exe", O_RDONLY) = 6 > sendfile(4, 6, NULL, 2147483663) = 1638400 > open("./bus", O_RDWR|O_CREAT|O_SYNC|O_NOATIME, 000) = 7 > write(7, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 22) <unfinished ...> > > This triggers a BUG in ext4_writepages(), where it checks if > the inode has inline data, just before deleting it: > > kernel BUG at fs/ext4/inode.c:2721! > invalid opcode: 0000 [#1] PREEMPT SMP KASAN > CPU: 0 PID: 359 Comm: repro Not tainted 5.19.0-rc8-00001-g31ba1e3b8305-dirty #15 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.fc36 04/01/2014 > RIP: 0010:ext4_writepages+0x363d/0x3660 > RSP: 0018:ffffc90000ccf260 EFLAGS: 00010293 > RAX: ffffffff81e1abcd RBX: 0000008000000000 RCX: ffff88810842a180 > RDX: 0000000000000000 RSI: 0000008000000000 RDI: 0000000000000000 > RBP: ffffc90000ccf650 R08: ffffffff81e17d58 R09: ffffed10222c680b > R10: dfffe910222c680c R11: 1ffff110222c680a R12: ffff888111634128 > R13: ffffc90000ccf880 R14: 0000008410000000 R15: 0000000000000001 > FS: 00007f72635d2640(0000) GS:ffff88811b000000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000565243379180 CR3: 000000010aa74000 CR4: 0000000000150eb0 > Call Trace: > <TASK> > do_writepages+0x397/0x640 > filemap_fdatawrite_wbc+0x151/0x1b0 > file_write_and_wait_range+0x1c9/0x2b0 > ext4_sync_file+0x19e/0xa00 > vfs_fsync_range+0x17b/0x190 > ext4_buffered_write_iter+0x488/0x530 > ext4_file_write_iter+0x449/0x1b90 > vfs_write+0xbcd/0xf40 > ksys_write+0x198/0x2c0 > __x64_sys_write+0x7b/0x90 > do_syscall_64+0x3d/0x90 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > </TASK> > > This can be prevented by forcing the inline data to be converted > and/or flushed beforehand. > This patch adds a call to ext4_convert_inline_data() just before > the BUG, which fixes the issue. > > Link: https://syzkaller.appspot.com/bug?id=a1e89d09bbbcbd5c4cb45db230ee28c822953984 > Reported-by: syzbot+bd13648a53ed6933ca49@syzkaller.appspotmail.com > Signed-off-by: Tadeusz Struk <tadeusz.struk@linaro.org> > --- > fs/ext4/inode.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 84c0eb55071d..de2aa2e79052 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -2717,6 +2717,10 @@ static int ext4_writepages(struct address_space *mapping, > ret = PTR_ERR(handle); > goto out_writepages; > } > + > + if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) > + WARN_ON(ext4_convert_inline_data(inode)); > + Hi Tadeusz, I don't think this is the right fix. We're in ext4_writepages, so at this point I don't think an inode should have any actual inline data in it. If it does it's a bug and the question is how did this get here? The inode is likely corrupted and it should have been noticed earliler and it should never get here. -Lukas > BUG_ON(ext4_test_inode_state(inode, > EXT4_STATE_MAY_INLINE_DATA)); > ext4_destroy_inline_data(handle, inode); > -- > 2.37.1 >
Hi Lukas, On 7/27/22 10:25, Lukas Czerner wrote: > I don't think this is the right fix. We're in ext4_writepages, so at > this point I don't think an inode should have any actual inline data in > it. If it does it's a bug and the question is how did this get here? > > The inode is likely corrupted and it should have been noticed earliler > and it should never get here. Yes, that was just an attempt fix something that I'm not quite familiar with. Jan sent already a patch for that fixes it: https://lore.kernel.org/all/20220727155753.13969-1-jack@suse.cz/
On Wed, Jul 27, 2022 at 10:40:25AM -0700, Tadeusz Struk wrote: > Hi Lukas, > On 7/27/22 10:25, Lukas Czerner wrote: > > I don't think this is the right fix. We're in ext4_writepages, so at > > this point I don't think an inode should have any actual inline data in > > it. If it does it's a bug and the question is how did this get here? > > > > The inode is likely corrupted and it should have been noticed earliler > > and it should never get here. > > Yes, that was just an attempt fix something that I'm not quite familiar > with. > > Jan sent already a patch for that fixes it: > https://lore.kernel.org/all/20220727155753.13969-1-jack@suse.cz/ > > -- > Thanks, > Tadeusz > Yeah, I just noticed sorry about that. I was missing the email context for some reason. Thanks! -Lukas
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 84c0eb55071d..de2aa2e79052 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2717,6 +2717,10 @@ static int ext4_writepages(struct address_space *mapping, ret = PTR_ERR(handle); goto out_writepages; } + + if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) + WARN_ON(ext4_convert_inline_data(inode)); + BUG_ON(ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)); ext4_destroy_inline_data(handle, inode);
Fix a syzbot issue, which triggers a BUG in ext4_writepags. The syzbot creates and monuts an ext4 fs image on /dev/loop0. The image is corrupted, which is probably the source of the problems, but the mount operation finishes successfully. Then the repro program creates a file on the mounted fs, and eventually it writes a buff of 22 zero bytes to it as below: memfd_create("syzkaller", 0) = 3 ftruncate(3, 2097152) = 0 pwrite64(3, " \0\0\0\0\2\0\0\31\0\0\0\220\1\0\0\17\0\0\0\0\0\0\0\2\0\0\0\6\0\0\0"..., 102, 1024) = 102 pwrite64(3, "\0\0\0\0\0\0\0\0\0\0\0\0\202\343g$\306\363L\252\204n\322\345'p3x\1\0@", 31, 1248) = 31 pwrite64(3, "\2\0\0\0\3\0\0\0\4\0\0\0\31\0\17\0\3\0\4\0\0\0\0\0\0\0\0\0\17\0.i", 32, 4096) = 32 pwrite64(3, "\177\0\0\0\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377"..., 4098, 8192) = 4098 pwrite64(3, "\355A\0\0\20\0\0\0\332\364e_\333\364e_\333\364e_\0\0\0\0\0\0\4\0\200\0\0\0"..., 61, 17408) = 61 openat(AT_FDCWD, "/dev/loop0", O_RDWR) = 4 ioctl(4, LOOP_SET_FD, 3) = 0 mkdir("./file0", 0777) = -1 EEXIST (File exists) mount("/dev/loop0", "./file0", "ext4", 0, ",errors=continue") = 0 openat(AT_FDCWD, "./file0", O_RDONLY|O_DIRECTORY) = 5 ioctl(4, LOOP_CLR_FD) = 0 close(4) = 0 close(3) = 0 chdir("./file0") = 0 creat("./bus", 000) = 3 open("./bus", O_RDWR|O_CREAT|O_NONBLOCK|O_SYNC|O_DIRECT|O_LARGEFILE|O_NOATIME, 000) = 4 openat(AT_FDCWD, "/proc/self/exe", O_RDONLY) = 6 sendfile(4, 6, NULL, 2147483663) = 1638400 open("./bus", O_RDWR|O_CREAT|O_SYNC|O_NOATIME, 000) = 7 write(7, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 22) <unfinished ...> This triggers a BUG in ext4_writepages(), where it checks if the inode has inline data, just before deleting it: kernel BUG at fs/ext4/inode.c:2721! invalid opcode: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 359 Comm: repro Not tainted 5.19.0-rc8-00001-g31ba1e3b8305-dirty #15 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.fc36 04/01/2014 RIP: 0010:ext4_writepages+0x363d/0x3660 RSP: 0018:ffffc90000ccf260 EFLAGS: 00010293 RAX: ffffffff81e1abcd RBX: 0000008000000000 RCX: ffff88810842a180 RDX: 0000000000000000 RSI: 0000008000000000 RDI: 0000000000000000 RBP: ffffc90000ccf650 R08: ffffffff81e17d58 R09: ffffed10222c680b R10: dfffe910222c680c R11: 1ffff110222c680a R12: ffff888111634128 R13: ffffc90000ccf880 R14: 0000008410000000 R15: 0000000000000001 FS: 00007f72635d2640(0000) GS:ffff88811b000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000565243379180 CR3: 000000010aa74000 CR4: 0000000000150eb0 Call Trace: <TASK> do_writepages+0x397/0x640 filemap_fdatawrite_wbc+0x151/0x1b0 file_write_and_wait_range+0x1c9/0x2b0 ext4_sync_file+0x19e/0xa00 vfs_fsync_range+0x17b/0x190 ext4_buffered_write_iter+0x488/0x530 ext4_file_write_iter+0x449/0x1b90 vfs_write+0xbcd/0xf40 ksys_write+0x198/0x2c0 __x64_sys_write+0x7b/0x90 do_syscall_64+0x3d/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd </TASK> This can be prevented by forcing the inline data to be converted and/or flushed beforehand. This patch adds a call to ext4_convert_inline_data() just before the BUG, which fixes the issue. Link: https://syzkaller.appspot.com/bug?id=a1e89d09bbbcbd5c4cb45db230ee28c822953984 Reported-by: syzbot+bd13648a53ed6933ca49@syzkaller.appspotmail.com Signed-off-by: Tadeusz Struk <tadeusz.struk@linaro.org> --- fs/ext4/inode.c | 4 ++++ 1 file changed, 4 insertions(+)