| Message ID | 20250212075242.988652-1-chao@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [f2fs-dev] f2fs: fix to avoid accessing uninitialized curseg | expand |
On 02/12, Chao Yu wrote: > syzbot reports a f2fs bug as below: > > F2FS-fs (loop3): Stopped filesystem due to reason: 7 > kworker/u8:7: attempt to access beyond end of device > BUG: unable to handle page fault for address: ffffed1604ea3dfa > RIP: 0010:get_ckpt_valid_blocks fs/f2fs/segment.h:361 [inline] > RIP: 0010:has_curseg_enough_space fs/f2fs/segment.h:570 [inline] > RIP: 0010:__get_secs_required fs/f2fs/segment.h:620 [inline] > RIP: 0010:has_not_enough_free_secs fs/f2fs/segment.h:633 [inline] > RIP: 0010:has_enough_free_secs+0x575/0x1660 fs/f2fs/segment.h:649 > <TASK> > f2fs_is_checkpoint_ready fs/f2fs/segment.h:671 [inline] > f2fs_write_inode+0x425/0x540 fs/f2fs/inode.c:791 > write_inode fs/fs-writeback.c:1525 [inline] > __writeback_single_inode+0x708/0x10d0 fs/fs-writeback.c:1745 > writeback_sb_inodes+0x820/0x1360 fs/fs-writeback.c:1976 > wb_writeback+0x413/0xb80 fs/fs-writeback.c:2156 > wb_do_writeback fs/fs-writeback.c:2303 [inline] > wb_workfn+0x410/0x1080 fs/fs-writeback.c:2343 > process_one_work kernel/workqueue.c:3236 [inline] > process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3317 > worker_thread+0x870/0xd30 kernel/workqueue.c:3398 > kthread+0x7a9/0x920 kernel/kthread.c:464 > ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > > Commit 8b10d3653735 ("f2fs: introduce FAULT_NO_SEGMENT") allows to trigger > no free segment fault in allocator, then it will update curseg->segno to > NULL_SEGNO, though, CP_ERROR_FLAG has been set, f2fs_write_inode() missed > to check the flag, and access invalid curseg->segno directly in below call > path, then resulting in panic: > > - f2fs_write_inode > - f2fs_is_checkpoint_ready > - has_enough_free_secs > - has_not_enough_free_secs > - __get_secs_required > - has_curseg_enough_space > - get_ckpt_valid_blocks > : access invalid curseg->segno > > To avoid this issue, let's: > - check CP_ERROR_FLAG flag in prior to f2fs_is_checkpoint_ready() in > f2fs_write_inode(). > - in has_curseg_enough_space(), a) verify status of curseg before accessing > its field, and b) grab curseg_mutex lock to avoid race condition. > > Fixes: 8b10d3653735 ("f2fs: introduce FAULT_NO_SEGMENT") > Reported-by: syzbot+b6b347b7a4ea1b2e29b6@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/all/67973c2b.050a0220.11b1bb.0089.GAE@google.com > Signed-off-by: Chao Yu <chao@kernel.org> > --- > fs/f2fs/inode.c | 7 +++++++ > fs/f2fs/segment.h | 27 ++++++++++++++++++++++----- > 2 files changed, 29 insertions(+), 5 deletions(-) > > diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c > index 02f1b69d03d8..5c1b515eab36 100644 > --- a/fs/f2fs/inode.c > +++ b/fs/f2fs/inode.c > @@ -799,6 +799,13 @@ int f2fs_write_inode(struct inode *inode, struct writeback_control *wbc) > !is_inode_flag_set(inode, FI_DIRTY_INODE)) > return 0; > > + /* > + * no need to update inode page, ultimately f2fs_evict_inode() will > + * clear dirty status of inode. > + */ > + if (f2fs_cp_error(sbi)) > + return -EIO; > + > if (!f2fs_is_checkpoint_ready(sbi)) { > f2fs_mark_inode_dirty_sync(inode, true); > return -ENOSPC; > diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h > index 943be4f1d6d2..e9fcf2b85b76 100644 > --- a/fs/f2fs/segment.h > +++ b/fs/f2fs/segment.h > @@ -559,15 +559,23 @@ static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi, > unsigned int node_blocks, unsigned int data_blocks, > unsigned int dent_blocks) > { > - > + struct curseg_info *curseg; > unsigned int segno, left_blocks, blocks; > int i; > > /* check current data/node sections in the worst case. */ > for (i = CURSEG_HOT_DATA; i < NR_PERSISTENT_LOG; i++) { > - segno = CURSEG_I(sbi, i)->segno; > - left_blocks = CAP_BLKS_PER_SEC(sbi) - > + curseg = CURSEG_I(sbi, i); > + > + mutex_lock(&curseg->curseg_mutex); > + if (!curseg->inited || curseg->segno == NULL_SEGNO) { > + left_blocks = 0; > + } else { > + segno = curseg->segno; > + left_blocks = CAP_BLKS_PER_SEC(sbi) - > get_ckpt_valid_blocks(sbi, segno, true); > + } > + mutex_unlock(&curseg->curseg_mutex); This looks a bit worrisome, as it'll block user-facing allocation. Can we have another way to prevent the issue? > > blocks = i <= CURSEG_COLD_DATA ? data_blocks : node_blocks; > if (blocks > left_blocks) > @@ -575,9 +583,18 @@ static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi, > } > > /* check current data section for dentry blocks. */ > - segno = CURSEG_I(sbi, CURSEG_HOT_DATA)->segno; > - left_blocks = CAP_BLKS_PER_SEC(sbi) - > + curseg = CURSEG_I(sbi, CURSEG_HOT_DATA); > + > + mutex_lock(&curseg->curseg_mutex); > + if (!curseg->inited || curseg->segno == NULL_SEGNO) { > + left_blocks = 0; > + } else { > + segno = curseg->segno; > + left_blocks = CAP_BLKS_PER_SEC(sbi) - > get_ckpt_valid_blocks(sbi, segno, true); > + } > + mutex_unlock(&curseg->curseg_mutex); > + > if (dent_blocks > left_blocks) > return false; > return true; > -- > 2.48.1.502.g6dc24dfdaf-goog
On 2/14/25 02:01, Jaegeuk Kim wrote: > On 02/12, Chao Yu wrote: >> syzbot reports a f2fs bug as below: >> >> F2FS-fs (loop3): Stopped filesystem due to reason: 7 >> kworker/u8:7: attempt to access beyond end of device >> BUG: unable to handle page fault for address: ffffed1604ea3dfa >> RIP: 0010:get_ckpt_valid_blocks fs/f2fs/segment.h:361 [inline] >> RIP: 0010:has_curseg_enough_space fs/f2fs/segment.h:570 [inline] >> RIP: 0010:__get_secs_required fs/f2fs/segment.h:620 [inline] >> RIP: 0010:has_not_enough_free_secs fs/f2fs/segment.h:633 [inline] >> RIP: 0010:has_enough_free_secs+0x575/0x1660 fs/f2fs/segment.h:649 >> <TASK> >> f2fs_is_checkpoint_ready fs/f2fs/segment.h:671 [inline] >> f2fs_write_inode+0x425/0x540 fs/f2fs/inode.c:791 >> write_inode fs/fs-writeback.c:1525 [inline] >> __writeback_single_inode+0x708/0x10d0 fs/fs-writeback.c:1745 >> writeback_sb_inodes+0x820/0x1360 fs/fs-writeback.c:1976 >> wb_writeback+0x413/0xb80 fs/fs-writeback.c:2156 >> wb_do_writeback fs/fs-writeback.c:2303 [inline] >> wb_workfn+0x410/0x1080 fs/fs-writeback.c:2343 >> process_one_work kernel/workqueue.c:3236 [inline] >> process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3317 >> worker_thread+0x870/0xd30 kernel/workqueue.c:3398 >> kthread+0x7a9/0x920 kernel/kthread.c:464 >> ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148 >> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 >> >> Commit 8b10d3653735 ("f2fs: introduce FAULT_NO_SEGMENT") allows to trigger >> no free segment fault in allocator, then it will update curseg->segno to >> NULL_SEGNO, though, CP_ERROR_FLAG has been set, f2fs_write_inode() missed >> to check the flag, and access invalid curseg->segno directly in below call >> path, then resulting in panic: >> >> - f2fs_write_inode >> - f2fs_is_checkpoint_ready >> - has_enough_free_secs >> - has_not_enough_free_secs >> - __get_secs_required >> - has_curseg_enough_space >> - get_ckpt_valid_blocks >> : access invalid curseg->segno >> >> To avoid this issue, let's: >> - check CP_ERROR_FLAG flag in prior to f2fs_is_checkpoint_ready() in >> f2fs_write_inode(). >> - in has_curseg_enough_space(), a) verify status of curseg before accessing >> its field, and b) grab curseg_mutex lock to avoid race condition. >> >> Fixes: 8b10d3653735 ("f2fs: introduce FAULT_NO_SEGMENT") >> Reported-by: syzbot+b6b347b7a4ea1b2e29b6@syzkaller.appspotmail.com >> Closes: https://lore.kernel.org/all/67973c2b.050a0220.11b1bb.0089.GAE@google.com >> Signed-off-by: Chao Yu <chao@kernel.org> >> --- >> fs/f2fs/inode.c | 7 +++++++ >> fs/f2fs/segment.h | 27 ++++++++++++++++++++++----- >> 2 files changed, 29 insertions(+), 5 deletions(-) >> >> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c >> index 02f1b69d03d8..5c1b515eab36 100644 >> --- a/fs/f2fs/inode.c >> +++ b/fs/f2fs/inode.c >> @@ -799,6 +799,13 @@ int f2fs_write_inode(struct inode *inode, struct writeback_control *wbc) >> !is_inode_flag_set(inode, FI_DIRTY_INODE)) >> return 0; >> >> + /* >> + * no need to update inode page, ultimately f2fs_evict_inode() will >> + * clear dirty status of inode. >> + */ >> + if (f2fs_cp_error(sbi)) >> + return -EIO; >> + >> if (!f2fs_is_checkpoint_ready(sbi)) { >> f2fs_mark_inode_dirty_sync(inode, true); >> return -ENOSPC; >> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h >> index 943be4f1d6d2..e9fcf2b85b76 100644 >> --- a/fs/f2fs/segment.h >> +++ b/fs/f2fs/segment.h >> @@ -559,15 +559,23 @@ static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi, >> unsigned int node_blocks, unsigned int data_blocks, >> unsigned int dent_blocks) >> { >> - >> + struct curseg_info *curseg; >> unsigned int segno, left_blocks, blocks; >> int i; >> >> /* check current data/node sections in the worst case. */ >> for (i = CURSEG_HOT_DATA; i < NR_PERSISTENT_LOG; i++) { >> - segno = CURSEG_I(sbi, i)->segno; >> - left_blocks = CAP_BLKS_PER_SEC(sbi) - >> + curseg = CURSEG_I(sbi, i); >> + >> + mutex_lock(&curseg->curseg_mutex); >> + if (!curseg->inited || curseg->segno == NULL_SEGNO) { >> + left_blocks = 0; >> + } else { >> + segno = curseg->segno; >> + left_blocks = CAP_BLKS_PER_SEC(sbi) - >> get_ckpt_valid_blocks(sbi, segno, true); >> + } >> + mutex_unlock(&curseg->curseg_mutex); > > This looks a bit worrisome, as it'll block user-facing allocation. Can we > have another way to prevent the issue? How about this? It'll be fine to use a temp valid segno in get_ckpt_valid_blocks(), it can get rid of curseg_mutex use. segno = CURSEG_I(sbi, i)->segno; if (!curseg->inited || segno == NULL_SEGNO) { left_blocks = 0; } else { ... Thanks, > >> >> blocks = i <= CURSEG_COLD_DATA ? data_blocks : node_blocks; >> if (blocks > left_blocks) >> @@ -575,9 +583,18 @@ static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi, >> } >> >> /* check current data section for dentry blocks. */ >> - segno = CURSEG_I(sbi, CURSEG_HOT_DATA)->segno; >> - left_blocks = CAP_BLKS_PER_SEC(sbi) - >> + curseg = CURSEG_I(sbi, CURSEG_HOT_DATA); >> + >> + mutex_lock(&curseg->curseg_mutex); >> + if (!curseg->inited || curseg->segno == NULL_SEGNO) { >> + left_blocks = 0; >> + } else { >> + segno = curseg->segno; >> + left_blocks = CAP_BLKS_PER_SEC(sbi) - >> get_ckpt_valid_blocks(sbi, segno, true); >> + } >> + mutex_unlock(&curseg->curseg_mutex); >> + >> if (dent_blocks > left_blocks) >> return false; >> return true; >> -- >> 2.48.1.502.g6dc24dfdaf-goog
diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c index 02f1b69d03d8..5c1b515eab36 100644 --- a/fs/f2fs/inode.c +++ b/fs/f2fs/inode.c @@ -799,6 +799,13 @@ int f2fs_write_inode(struct inode *inode, struct writeback_control *wbc) !is_inode_flag_set(inode, FI_DIRTY_INODE)) return 0; + /* + * no need to update inode page, ultimately f2fs_evict_inode() will + * clear dirty status of inode. + */ + if (f2fs_cp_error(sbi)) + return -EIO; + if (!f2fs_is_checkpoint_ready(sbi)) { f2fs_mark_inode_dirty_sync(inode, true); return -ENOSPC; diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h index 943be4f1d6d2..e9fcf2b85b76 100644 --- a/fs/f2fs/segment.h +++ b/fs/f2fs/segment.h @@ -559,15 +559,23 @@ static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi, unsigned int node_blocks, unsigned int data_blocks, unsigned int dent_blocks) { - + struct curseg_info *curseg; unsigned int segno, left_blocks, blocks; int i; /* check current data/node sections in the worst case. */ for (i = CURSEG_HOT_DATA; i < NR_PERSISTENT_LOG; i++) { - segno = CURSEG_I(sbi, i)->segno; - left_blocks = CAP_BLKS_PER_SEC(sbi) - + curseg = CURSEG_I(sbi, i); + + mutex_lock(&curseg->curseg_mutex); + if (!curseg->inited || curseg->segno == NULL_SEGNO) { + left_blocks = 0; + } else { + segno = curseg->segno; + left_blocks = CAP_BLKS_PER_SEC(sbi) - get_ckpt_valid_blocks(sbi, segno, true); + } + mutex_unlock(&curseg->curseg_mutex); blocks = i <= CURSEG_COLD_DATA ? data_blocks : node_blocks; if (blocks > left_blocks) @@ -575,9 +583,18 @@ static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi, } /* check current data section for dentry blocks. */ - segno = CURSEG_I(sbi, CURSEG_HOT_DATA)->segno; - left_blocks = CAP_BLKS_PER_SEC(sbi) - + curseg = CURSEG_I(sbi, CURSEG_HOT_DATA); + + mutex_lock(&curseg->curseg_mutex); + if (!curseg->inited || curseg->segno == NULL_SEGNO) { + left_blocks = 0; + } else { + segno = curseg->segno; + left_blocks = CAP_BLKS_PER_SEC(sbi) - get_ckpt_valid_blocks(sbi, segno, true); + } + mutex_unlock(&curseg->curseg_mutex); + if (dent_blocks > left_blocks) return false; return true;
syzbot reports a f2fs bug as below: F2FS-fs (loop3): Stopped filesystem due to reason: 7 kworker/u8:7: attempt to access beyond end of device BUG: unable to handle page fault for address: ffffed1604ea3dfa RIP: 0010:get_ckpt_valid_blocks fs/f2fs/segment.h:361 [inline] RIP: 0010:has_curseg_enough_space fs/f2fs/segment.h:570 [inline] RIP: 0010:__get_secs_required fs/f2fs/segment.h:620 [inline] RIP: 0010:has_not_enough_free_secs fs/f2fs/segment.h:633 [inline] RIP: 0010:has_enough_free_secs+0x575/0x1660 fs/f2fs/segment.h:649 <TASK> f2fs_is_checkpoint_ready fs/f2fs/segment.h:671 [inline] f2fs_write_inode+0x425/0x540 fs/f2fs/inode.c:791 write_inode fs/fs-writeback.c:1525 [inline] __writeback_single_inode+0x708/0x10d0 fs/fs-writeback.c:1745 writeback_sb_inodes+0x820/0x1360 fs/fs-writeback.c:1976 wb_writeback+0x413/0xb80 fs/fs-writeback.c:2156 wb_do_writeback fs/fs-writeback.c:2303 [inline] wb_workfn+0x410/0x1080 fs/fs-writeback.c:2343 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3317 worker_thread+0x870/0xd30 kernel/workqueue.c:3398 kthread+0x7a9/0x920 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Commit 8b10d3653735 ("f2fs: introduce FAULT_NO_SEGMENT") allows to trigger no free segment fault in allocator, then it will update curseg->segno to NULL_SEGNO, though, CP_ERROR_FLAG has been set, f2fs_write_inode() missed to check the flag, and access invalid curseg->segno directly in below call path, then resulting in panic: - f2fs_write_inode - f2fs_is_checkpoint_ready - has_enough_free_secs - has_not_enough_free_secs - __get_secs_required - has_curseg_enough_space - get_ckpt_valid_blocks : access invalid curseg->segno To avoid this issue, let's: - check CP_ERROR_FLAG flag in prior to f2fs_is_checkpoint_ready() in f2fs_write_inode(). - in has_curseg_enough_space(), a) verify status of curseg before accessing its field, and b) grab curseg_mutex lock to avoid race condition. Fixes: 8b10d3653735 ("f2fs: introduce FAULT_NO_SEGMENT") Reported-by: syzbot+b6b347b7a4ea1b2e29b6@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/67973c2b.050a0220.11b1bb.0089.GAE@google.com Signed-off-by: Chao Yu <chao@kernel.org> --- fs/f2fs/inode.c | 7 +++++++ fs/f2fs/segment.h | 27 ++++++++++++++++++++++----- 2 files changed, 29 insertions(+), 5 deletions(-)