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erofs: reject inodes with negative i_size

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Negative i_size is never supported, although crafted images with inodes
having negative i_size will NOT lead to security issues in our current
codebase:

The following image can verify this (gzip+base64 encoded):

H4sICCmk4mYAA3Rlc3QuaW1nAGNgGAWjYBSMVPDo4dcH3jP2aTED2TwMKgxMUHHNJY/SQDQX
LxcDIw3tZwXit44MDNpQ/n8gQJZ/vxjijosPuSyZ0DUDgQqcZoKzVYFsDShbHeh6PT29ktTi
Eqz2g/y2pBFiLxDMh4lhs5+W4TAKRsEoGAWjYBSMglEwCkYBPQAAS2DbowAQAAA=

Mark as bad inodes for such corrupted inodes explicitly.

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240912083538.3011860-1-hsiangkao@linux.alibaba.com
This commit is contained in:
Gao Xiang 2024-09-12 16:35:38 +08:00
parent 7c3ca1838a
commit 025497e1d1
1 changed files with 6 additions and 3 deletions
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9
fs/erofs/inode.c
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@ -5,7 +5,6 @@
* Copyright (C) 2021, Alibaba Cloud * Copyright (C) 2021, Alibaba Cloud
*/ */
#include "xattr.h" #include "xattr.h"
#include <trace/events/erofs.h> #include <trace/events/erofs.h>
static int erofs_fill_symlink(struct inode *inode, void *kaddr, static int erofs_fill_symlink(struct inode *inode, void *kaddr,
@ -16,7 +15,7 @@ static int erofs_fill_symlink(struct inode *inode, void *kaddr,
m_pofs += vi->xattr_isize; m_pofs += vi->xattr_isize;
/* check if it cannot be handled with fast symlink scheme */ /* check if it cannot be handled with fast symlink scheme */
if (vi->datalayout != EROFS_INODE_FLAT_INLINE || inode->i_size < 0 || if (vi->datalayout != EROFS_INODE_FLAT_INLINE ||
check_add_overflow(m_pofs, inode->i_size, &off) || check_add_overflow(m_pofs, inode->i_size, &off) ||
off > i_blocksize(inode)) off > i_blocksize(inode))
return 0; return 0;
@ -131,6 +130,11 @@ static int erofs_read_inode(struct inode *inode)
goto err_out; goto err_out;
} }
if (unlikely(inode->i_size < 0)) {
erofs_err(sb, "negative i_size @ nid %llu", vi->nid);
err = -EFSCORRUPTED;
goto err_out;
}
switch (inode->i_mode & S_IFMT) { switch (inode->i_mode & S_IFMT) {
case S_IFREG: case S_IFREG:
case S_IFDIR: case S_IFDIR:
@ -186,7 +190,6 @@ static int erofs_read_inode(struct inode *inode)
inode->i_blocks = round_up(inode->i_size, sb->s_blocksize) >> 9; inode->i_blocks = round_up(inode->i_size, sb->s_blocksize) >> 9;
else else
inode->i_blocks = nblks << (sb->s_blocksize_bits - 9); inode->i_blocks = nblks << (sb->s_blocksize_bits - 9);
err_out: err_out:
DBG_BUGON(err); DBG_BUGON(err);
erofs_put_metabuf(&buf); erofs_put_metabuf(&buf);