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. Signed-off-by: Gao Xiang <[email protected]> --- fs/erofs/inode.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c index 7a98df664814..db29190656eb 100644 --- a/fs/erofs/inode.c +++ b/fs/erofs/inode.c @@ -5,7 +5,6 @@ * Copyright (C) 2021, Alibaba Cloud */ #include "xattr.h" - #include <trace/events/erofs.h> 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; /* 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) || off > i_blocksize(inode)) return 0; @@ -131,6 +130,11 @@ static int erofs_read_inode(struct inode *inode) 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) { case S_IFREG: 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; else inode->i_blocks = nblks << (sb->s_blocksize_bits - 9); - err_out: DBG_BUGON(err); erofs_put_metabuf(&buf); -- 2.43.5
