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authorRyusuke Konishi <[email protected]>2024-06-23 14:11:34 +0900
committerAndrew Morton <[email protected]>2024-07-03 19:30:16 -0700
commit49ae997f8f0d5e268bbd271c5fd66166ce8287fe (patch)
tree3ca54b075084c6a8c2d139c45a2271399f0685af
parent1ab8425091dba7ce8bf59e09e183aaca6c2a12ac (diff)
nilfs2: add missing check for inode numbers on directory entries
Syzbot reported that mounting and unmounting a specific pattern of corrupted nilfs2 filesystem images causes a use-after-free of metadata file inodes, which triggers a kernel bug in lru_add_fn(). As Jan Kara pointed out, this is because the link count of a metadata file gets corrupted to 0, and nilfs_evict_inode(), which is called from iput(), tries to delete that inode (ifile inode in this case). The inconsistency occurs because directories containing the inode numbers of these metadata files that should not be visible in the namespace are read without checking. Fix this issue by treating the inode numbers of these internal files as errors in the sanity check helper when reading directory folios/pages. Also thanks to Hillf Danton and Matthew Wilcox for their initial mm-layer analysis. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Ryusuke Konishi <[email protected]> Reported-by: [email protected] Closes: https://syzkaller.appspot.com/bug?extid=d79afb004be235636ee8 Reported-by: Jan Kara <[email protected]> Closes: https://lkml.kernel.org/r/20240617075758.wewhukbrjod5fp5o@quack3 Tested-by: Ryusuke Konishi <[email protected]> Cc: Hillf Danton <[email protected]> Cc: Matthew Wilcox (Oracle) <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]>
-rw-r--r--fs/nilfs2/dir.c6
-rw-r--r--fs/nilfs2/nilfs.h5
2 files changed, 11 insertions, 0 deletions
diff --git a/fs/nilfs2/dir.c b/fs/nilfs2/dir.c
index 52e50b1b7f22..dddfa604491a 100644
--- a/fs/nilfs2/dir.c
+++ b/fs/nilfs2/dir.c
@@ -135,6 +135,9 @@ static bool nilfs_check_folio(struct folio *folio, char *kaddr)
goto Enamelen;
if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
goto Espan;
+ if (unlikely(p->inode &&
+ NILFS_PRIVATE_INODE(le64_to_cpu(p->inode))))
+ goto Einumber;
}
if (offs != limit)
goto Eend;
@@ -160,6 +163,9 @@ Enamelen:
goto bad_entry;
Espan:
error = "directory entry across blocks";
+ goto bad_entry;
+Einumber:
+ error = "disallowed inode number";
bad_entry:
nilfs_error(sb,
"bad entry in directory #%lu: %s - offset=%lu, inode=%lu, rec_len=%zd, name_len=%d",
diff --git a/fs/nilfs2/nilfs.h b/fs/nilfs2/nilfs.h
index 7e39e277c77f..4017f7856440 100644
--- a/fs/nilfs2/nilfs.h
+++ b/fs/nilfs2/nilfs.h
@@ -121,6 +121,11 @@ enum {
((ino) >= NILFS_FIRST_INO(sb) || \
((ino) < NILFS_USER_INO && (NILFS_SYS_INO_BITS & BIT(ino))))
+#define NILFS_PRIVATE_INODE(ino) ({ \
+ ino_t __ino = (ino); \
+ ((__ino) < NILFS_USER_INO && (__ino) != NILFS_ROOT_INO && \
+ (__ino) != NILFS_SKETCH_INO); })
+
/**
* struct nilfs_transaction_info: context information for synchronization
* @ti_magic: Magic number