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authorAl Viro <viro@ftp.linux.org.uk>2006-03-15 21:41:59 +0000
committerGreg Kroah-Hartman <gregkh@suse.de>2006-03-27 23:00:23 -0800
commit6d4da66240b9fec065933928043b1365f97ab724 (patch)
treeded2ab6988b6164df2d22d1167c6e0f57485a87d
parent107d25ba4fcacf8e29bcad240b95fd9ef7314dac (diff)
[PATCH] Fix ext2 readdir f_pos re-validation logic
This fixes not one, but _two_, silly (but admittedly hard to hit) bugs in the ext2 filesystem "readdir()" function. It also cleans up the code to avoid the unnecessary goto mess. The bugs were related to re-valiating the f_pos value after somebody had either done an "lseek()" on the directory to an invalid offset, or when the offset had become invalid due to a file being unlinked in the directory. The code would not only set the f_version too eagerly, it would also not update f_pos appropriately for when the offset fixup took place. When that happened, we'd occasionally subsequently fail the readdir() even when we shouldn't (no real harm done, but an ugly printk, and obviously you would end up not necessarily seeing all entries). Thanks to Masoud Sharbiani <masouds@google.com> who noticed the problem and had a test-case for it, and also fixed up a thinko in the first version of this patch. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Acked-by: Masoud Sharbiani <masouds@google.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--fs/ext2/dir.c28
1 files changed, 12 insertions, 16 deletions
diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
index 5b5f52876b42..e7a1286e07c3 100644
--- a/fs/ext2/dir.c
+++ b/fs/ext2/dir.c
@@ -256,11 +256,10 @@ ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
unsigned long npages = dir_pages(inode);
unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
unsigned char *types = NULL;
- int need_revalidate = (filp->f_version != inode->i_version);
- int ret;
+ int need_revalidate = filp->f_version != inode->i_version;
if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
- goto success;
+ return 0;
if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
types = ext2_filetype_table;
@@ -275,12 +274,15 @@ ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
"bad page in #%lu",
inode->i_ino);
filp->f_pos += PAGE_CACHE_SIZE - offset;
- ret = -EIO;
- goto done;
+ return -EIO;
}
kaddr = page_address(page);
- if (need_revalidate) {
- offset = ext2_validate_entry(kaddr, offset, chunk_mask);
+ if (unlikely(need_revalidate)) {
+ if (offset) {
+ offset = ext2_validate_entry(kaddr, offset, chunk_mask);
+ filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
+ }
+ filp->f_version = inode->i_version;
need_revalidate = 0;
}
de = (ext2_dirent *)(kaddr+offset);
@@ -289,9 +291,8 @@ ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
if (de->rec_len == 0) {
ext2_error(sb, __FUNCTION__,
"zero-length directory entry");
- ret = -EIO;
ext2_put_page(page);
- goto done;
+ return -EIO;
}
if (de->inode) {
int over;
@@ -306,19 +307,14 @@ ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
le32_to_cpu(de->inode), d_type);
if (over) {
ext2_put_page(page);
- goto success;
+ return 0;
}
}
filp->f_pos += le16_to_cpu(de->rec_len);
}
ext2_put_page(page);
}
-
-success:
- ret = 0;
-done:
- filp->f_version = inode->i_version;
- return ret;
+ return 0;
}
/*