Messages in this thread | | | Date | Wed, 16 Apr 2014 18:11:14 -0700 | From | Alexey Khoroshilov <> | Subject | Re: f2fs: BUG_ON() is triggered when mount valid f2fs filesystem |
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Hi,
But would not ability to trigger BUG_ON by mounting a crafted image considered as an issue having security implications?
Regards, Alexey
On 16.04.2014 16:35, Jaegeuk Kim wrote: > Hi, > > 2014-04-16 (수), 13:11 +0400, Andrey Tsyvarev: >> Hi, >> >> With this patch mounting of the image continues to fail (with similar >> BUG_ON). >> But when image is formatted again (and steps mentioned in the previous >> message are performed), >> mounting of it is now succeed. >> >> Is this is a true purpose of the patch? > Indeed. The patch solves there-in root cause. > But, if you're trying to use the failed image again, simply you can skip > the errorneous part by: > > # mount ... -o disable_roll_forward ... > > Once sync or umount whatever checkpoint is done after that, the image > will be mounted without "disable_roll_forward". > > Thanks, > >> 15.04.2014 15:04, Jaegeuk Kim пишет: >>> Hi, >>> >>> Thank you for the report. >>> I retrieved the fault image and found out that previous garbage data >>> wreak such the wrong behaviors. >>> So, I wrote the following patch that fills one zero-block at the >>> checkpoint procedure. >>> If the underlying device supports discard, I expect that it mostly >>> doesn't incur any performance regression significantly. >>> >>> Could you test this patch? >>> >>> >From 60588ceb7277aae2a79e7f67f5217d1256720d78 Mon Sep 17 00:00:00 2001 >>> From: Jaegeuk Kim <jaegeuk.kim@samsung.com> >>> Date: Tue, 15 Apr 2014 13:57:55 +0900 >>> Subject: [PATCH] f2fs: avoid to conduct roll-forward due to the remained >>> garbage blocks >>> >>> The f2fs always scans the next chain of direct node blocks. >>> But some garbage blocks are able to be remained due to no discard >>> support or >>> SSR triggers. >>> This occasionally wreaks recovering wrong inodes that were used or >>> BUG_ONs >>> due to reallocating node ids as follows. >>> >>> When mount this f2fs image: >>> http://linuxtesting.org/downloads/f2fs_fault_image.zip >>> BUG_ON is triggered in f2fs driver (messages below are generated on >>> kernel 3.13.2; for other kernels output is similar): >>> >>> kernel BUG at fs/f2fs/node.c:215! >>> Call Trace: >>> [<ffffffffa032ebad>] recover_inode_page+0x1fd/0x3e0 [f2fs] >>> [<ffffffff811446e7>] ? __lock_page+0x67/0x70 >>> [<ffffffff81089990>] ? autoremove_wake_function+0x50/0x50 >>> [<ffffffffa0337788>] recover_fsync_data+0x1398/0x15d0 [f2fs] >>> [<ffffffff812b9e5c>] ? selinux_d_instantiate+0x1c/0x20 >>> [<ffffffff811cb20b>] ? d_instantiate+0x5b/0x80 >>> [<ffffffffa0321044>] f2fs_fill_super+0xb04/0xbf0 [f2fs] >>> [<ffffffff811b861e>] ? mount_bdev+0x7e/0x210 >>> [<ffffffff811b8769>] mount_bdev+0x1c9/0x210 >>> [<ffffffffa0320540>] ? validate_superblock+0x210/0x210 [f2fs] >>> [<ffffffffa031cf8d>] f2fs_mount+0x1d/0x30 [f2fs] >>> [<ffffffff811b9497>] mount_fs+0x47/0x1c0 >>> [<ffffffff81166e00>] ? __alloc_percpu+0x10/0x20 >>> [<ffffffff811d4032>] vfs_kern_mount+0x72/0x110 >>> [<ffffffff811d6763>] do_mount+0x493/0x910 >>> [<ffffffff811615cb>] ? strndup_user+0x5b/0x80 >>> [<ffffffff811d6c70>] SyS_mount+0x90/0xe0 >>> [<ffffffff8166f8d9>] system_call_fastpath+0x16/0x1b >>> >>> Found by Linux File System Verification project (linuxtesting.org). >>> >>> Reported-by: Andrey Tsyvarev <tsyvarev@ispras.ru> >>> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com> >>> --- >>> fs/f2fs/checkpoint.c | 6 ++++++ >>> fs/f2fs/f2fs.h | 1 + >>> fs/f2fs/segment.c | 17 +++++++++++++++-- >>> 3 files changed, 22 insertions(+), 2 deletions(-) >>> >>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c >>> index 4aa521a..890e23d 100644 >>> --- a/fs/f2fs/checkpoint.c >>> +++ b/fs/f2fs/checkpoint.c >>> @@ -762,6 +762,12 @@ static void do_checkpoint(struct f2fs_sb_info *sbi, >>> bool is_umount) >>> void *kaddr; >>> int i; >>> >>> + /* >>> + * This avoids to conduct wrong roll-forward operations and uses >>> + * metapages, so should be called prior to sync_meta_pages below. >>> + */ >>> + discard_next_dnode(sbi); >>> + >>> /* Flush all the NAT/SIT pages */ >>> while (get_pages(sbi, F2FS_DIRTY_META)) >>> sync_meta_pages(sbi, META, LONG_MAX); >>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h >>> index 2ecac83..2c5a5da 100644 >>> --- a/fs/f2fs/f2fs.h >>> +++ b/fs/f2fs/f2fs.h >>> @@ -1179,6 +1179,7 @@ int f2fs_issue_flush(struct f2fs_sb_info *); >>> void invalidate_blocks(struct f2fs_sb_info *, block_t); >>> void refresh_sit_entry(struct f2fs_sb_info *, block_t, block_t); >>> void clear_prefree_segments(struct f2fs_sb_info *); >>> +void discard_next_dnode(struct f2fs_sb_info *); >>> int npages_for_summary_flush(struct f2fs_sb_info *); >>> void allocate_new_segments(struct f2fs_sb_info *); >>> struct page *get_sum_page(struct f2fs_sb_info *, unsigned int); >>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c >>> index 1e264e7..9993f94 100644 >>> --- a/fs/f2fs/segment.c >>> +++ b/fs/f2fs/segment.c >>> @@ -335,13 +335,26 @@ static void locate_dirty_segment(struct >>> f2fs_sb_info *sbi, unsigned int segno) >>> mutex_unlock(&dirty_i->seglist_lock); >>> } >>> >>> -static void f2fs_issue_discard(struct f2fs_sb_info *sbi, >>> +static int f2fs_issue_discard(struct f2fs_sb_info *sbi, >>> block_t blkstart, block_t blklen) >>> { >>> sector_t start = SECTOR_FROM_BLOCK(sbi, blkstart); >>> sector_t len = SECTOR_FROM_BLOCK(sbi, blklen); >>> - blkdev_issue_discard(sbi->sb->s_bdev, start, len, GFP_NOFS, 0); >>> trace_f2fs_issue_discard(sbi->sb, blkstart, blklen); >>> + return blkdev_issue_discard(sbi->sb->s_bdev, start, len, GFP_NOFS, 0); >>> +} >>> + >>> +void discard_next_dnode(struct f2fs_sb_info *sbi) >>> +{ >>> + struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_WARM_NODE); >>> + block_t blkaddr = NEXT_FREE_BLKADDR(sbi, curseg); >>> + >>> + if (f2fs_issue_discard(sbi, blkaddr, 1)) { >>> + struct page *page = grab_meta_page(sbi, blkaddr); >>> + /* zero-filled page */ >>> + set_page_dirty(page); >>> + f2fs_put_page(page, 1); >>> + } >>> } >>> >>> static void add_discard_addrs(struct f2fs_sb_info *sbi,
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