5.0-stable review patch. If anyone has any objections, please let me know.
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From: Gao Xiang gaoxiang25@huawei.com
commit 33bac912840fe64dbc15556302537dc6a17cac63 upstream.
After commit 419d6efc50e9, kernel cannot be crashed in the namei path. However, corrupted nameoff can do harm in the process of readdir for scenerios without dm-verity as well. Fix it now.
Fixes: 3aa8ec716e52 ("staging: erofs: add directory operations") Cc: stable@vger.kernel.org # 4.19+ Signed-off-by: Gao Xiang gaoxiang25@huawei.com Reviewed-by: Chao Yu yuchao0@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/staging/erofs/dir.c | 45 ++++++++++++++++++++++++-------------------- 1 file changed, 25 insertions(+), 20 deletions(-)
--- a/drivers/staging/erofs/dir.c +++ b/drivers/staging/erofs/dir.c @@ -23,6 +23,21 @@ static const unsigned char erofs_filetyp [EROFS_FT_SYMLINK] = DT_LNK, };
+static void debug_one_dentry(unsigned char d_type, const char *de_name, + unsigned int de_namelen) +{ +#ifdef CONFIG_EROFS_FS_DEBUG + /* since the on-disk name could not have the trailing '\0' */ + unsigned char dbg_namebuf[EROFS_NAME_LEN + 1]; + + memcpy(dbg_namebuf, de_name, de_namelen); + dbg_namebuf[de_namelen] = '\0'; + + debugln("found dirent %s de_len %u d_type %d", dbg_namebuf, + de_namelen, d_type); +#endif +} + static int erofs_fill_dentries(struct dir_context *ctx, void *dentry_blk, unsigned int *ofs, unsigned int nameoff, unsigned int maxsize) @@ -33,14 +48,10 @@ static int erofs_fill_dentries(struct di de = dentry_blk + *ofs; while (de < end) { const char *de_name; - int de_namelen; + unsigned int de_namelen; unsigned char d_type; -#ifdef CONFIG_EROFS_FS_DEBUG - unsigned int dbg_namelen; - unsigned char dbg_namebuf[EROFS_NAME_LEN]; -#endif
- if (unlikely(de->file_type < EROFS_FT_MAX)) + if (de->file_type < EROFS_FT_MAX) d_type = erofs_filetype_table[de->file_type]; else d_type = DT_UNKNOWN; @@ -48,26 +59,20 @@ static int erofs_fill_dentries(struct di nameoff = le16_to_cpu(de->nameoff); de_name = (char *)dentry_blk + nameoff;
- de_namelen = unlikely(de + 1 >= end) ? - /* last directory entry */ - strnlen(de_name, maxsize - nameoff) : - le16_to_cpu(de[1].nameoff) - nameoff; + /* the last dirent in the block? */ + if (de + 1 >= end) + de_namelen = strnlen(de_name, maxsize - nameoff); + else + de_namelen = le16_to_cpu(de[1].nameoff) - nameoff;
/* a corrupted entry is found */ - if (unlikely(de_namelen < 0)) { + if (unlikely(nameoff + de_namelen > maxsize || + de_namelen > EROFS_NAME_LEN)) { DBG_BUGON(1); return -EIO; }
-#ifdef CONFIG_EROFS_FS_DEBUG - dbg_namelen = min(EROFS_NAME_LEN - 1, de_namelen); - memcpy(dbg_namebuf, de_name, dbg_namelen); - dbg_namebuf[dbg_namelen] = '\0'; - - debugln("%s, found de_name %s de_len %d d_type %d", __func__, - dbg_namebuf, de_namelen, d_type); -#endif - + debug_one_dentry(d_type, de_name, de_namelen); if (!dir_emit(ctx, de_name, de_namelen, le64_to_cpu(de->nid), d_type)) /* stopped by some reason */