From d1bdf22461e9f0638d4ddca0ccccfe61f8a653cf Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Stefan=20Br=C3=BCns?= Date: Sun, 9 Oct 2016 20:15:27 +0200 Subject: ext4: Fix handling of direntlen in unlink_filename MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The direntlen checks were quite bogus, i.e. the loop termination used "len + offset == blocksize" (exact match only), and checked for a direntlen less than 0. The latter can never happen as the len is unsigned, this has been reported by Coverity, CID 153384. Use the same code as in search_dir for directory traversal. This code has the correct checks for direntlen >= sizeof(struct dirent), and offset < blocksize. Signed-off-by: Stefan Brüns Reported-by: Coverity (CID: 153383, 153384) Reviewed-by: Tom Rini Reviewed-by: Lukasz Majewski --- fs/ext4/ext4_common.c | 45 +++++++++++++++++---------------------------- 1 file changed, 17 insertions(+), 28 deletions(-) (limited to 'fs') diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c index 699a640d2d..0c11ddb1b5 100644 --- a/fs/ext4/ext4_common.c +++ b/fs/ext4/ext4_common.c @@ -854,16 +854,15 @@ fail: static int unlink_filename(char *filename, unsigned int blknr) { - int templength = 0; - int status, inodeno; - int found = 0; + int status; + int inodeno = 0; int offset; char *block_buffer = NULL; struct ext2_dirent *dir = NULL; - struct ext2_dirent *previous_dir = NULL; - char *ptr = NULL; + struct ext2_dirent *previous_dir; struct ext_filesystem *fs = get_fs(); int ret = -1; + char *direntname; block_buffer = zalloc(fs->blksz); if (!block_buffer) @@ -877,20 +876,18 @@ static int unlink_filename(char *filename, unsigned int blknr) if (ext4fs_log_journal(block_buffer, blknr)) goto fail; - dir = (struct ext2_dirent *)block_buffer; - ptr = (char *)dir; offset = 0; - while (le16_to_cpu(dir->direntlen) >= 0) { - /* - * blocksize-offset because last - * directory length i.e., *dir->direntlen - * is free availble space in the block that - * means it is a last entry of directory entry - */ + do { + previous_dir = dir; + dir = (struct ext2_dirent *)(block_buffer + offset); + direntname = (char *)(dir) + sizeof(struct ext2_dirent); + + int direntlen = le16_to_cpu(dir->direntlen); + if (direntlen < sizeof(struct ext2_dirent)) + break; + if (dir->inode && (strlen(filename) == dir->namelen) && - (strncmp(ptr + sizeof(struct ext2_dirent), - filename, dir->namelen) == 0)) { - printf("file found, deleting\n"); + (strncmp(direntname, filename, dir->namelen) == 0)) { inodeno = le32_to_cpu(dir->inode); if (previous_dir) { uint16_t new_len; @@ -900,23 +897,15 @@ static int unlink_filename(char *filename, unsigned int blknr) } else { dir->inode = 0; } - found = 1; break; } - if (fs->blksz - offset == le16_to_cpu(dir->direntlen)) - break; + offset += direntlen; - /* traversing the each directory entry */ - templength = le16_to_cpu(dir->direntlen); - offset = offset + templength; - previous_dir = dir; - dir = (struct ext2_dirent *)((char *)dir + templength); - ptr = (char *)dir; - } + } while (offset < fs->blksz); + if (inodeno > 0) { - if (found == 1) { if (ext4fs_put_metadata(block_buffer, blknr)) goto fail; ret = inodeno; -- cgit v1.2.3