Messages in this thread Patch in this message | | | Date | Fri, 25 Jan 2002 01:35:02 +0100 (MET) | From | Mikael Pettersson <> | Subject | [PATCH] ext2 FS corruption in 2.5.3-pre[3-5] |
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Al & Linus,
There is a file system corruption problem in 2.5.3-pre[3-5], caused by leaking uninitialised memory to in-core and later on-disk inodes.
I can easily observe the problem by creating lots of files in an ext2 FS, reboot to single-user, and fsck the ext2 FS partition. fsck will then give a lot of warnings about:
"i_fsize for inode NNN (...) is XX, should be zero"
where XX is a random non-zero 8-bit number.
I traced it to the pre2->pre3 transition, which contains: > - Al Viro: VFS inode allocation moved down to filesystem, trim inodes
When FS-specific data was stored in inode->u, that data was cleared by the memset() in fs/inode.c:alloc_inode(). The FS didn't have to bother. Since -pre3, ext2 (and perhaps other FSs, I haven't checked) uses an in-core inode layout consisting of an FS-specific head followed by the generic inode. ext2 allocates these in fs/ext2/super.c:ext2_alloc_inode(), but doesn't clear the ext2-specific fields. fs/inode.c:alloc_inode() neither knows about these fields nor clears them, so the ext2-specific data remains uninitialised when the new inode is returned for use. Ouch.
The patch below fixes this by adding the missing memset() to fs/ext2/super.c:ext2_alloc_inode(). Works fine over here.
/Mikael
--- linux-2.5.3-pre5/fs/ext2/super.c.~1~ Fri Jan 25 00:03:58 2002 +++ linux-2.5.3-pre5/fs/ext2/super.c Fri Jan 25 00:35:12 2002 @@ -155,6 +155,7 @@ ei = (struct ext2_inode_info *)kmem_cache_alloc(ext2_inode_cachep, SLAB_KERNEL); if (!ei) return NULL; + memset(ei, 0, offsetof(struct ext2_inode_info, vfs_inode)); return &ei->vfs_inode; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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