From 0e5cc9a40ada6046e6bc3bdfcd0c0d7e4b706b14 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Thu, 18 Dec 2014 22:37:50 +0100 Subject: udf: Check path length when reading symlink Symlink reading code does not check whether the resulting path fits into the page provided by the generic code. This isn't as easy as just checking the symlink size because of various encoding conversions we perform on path. So we have to check whether there is still enough space in the buffer on the fly. CC: stable@vger.kernel.org Reported-by: Carl Henrik Lunde Signed-off-by: Jan Kara --- fs/udf/symlink.c | 31 ++++++++++++++++++++++++++----- 1 file changed, 26 insertions(+), 5 deletions(-) (limited to 'fs/udf/symlink.c') diff --git a/fs/udf/symlink.c b/fs/udf/symlink.c index c3aa6fafd6cf..0f1b3a2654b9 100644 --- a/fs/udf/symlink.c +++ b/fs/udf/symlink.c @@ -30,13 +30,16 @@ #include #include "udf_i.h" -static void udf_pc_to_char(struct super_block *sb, unsigned char *from, - int fromlen, unsigned char *to) +static int udf_pc_to_char(struct super_block *sb, unsigned char *from, + int fromlen, unsigned char *to, int tolen) { struct pathComponent *pc; int elen = 0; + int comp_len; unsigned char *p = to; + /* Reserve one byte for terminating \0 */ + tolen--; while (elen < fromlen) { pc = (struct pathComponent *)(from + elen); switch (pc->componentType) { @@ -49,22 +52,37 @@ static void udf_pc_to_char(struct super_block *sb, unsigned char *from, break; /* Fall through */ case 2: + if (tolen == 0) + return -ENAMETOOLONG; p = to; *p++ = '/'; + tolen--; break; case 3: + if (tolen < 3) + return -ENAMETOOLONG; memcpy(p, "../", 3); p += 3; + tolen -= 3; break; case 4: + if (tolen < 2) + return -ENAMETOOLONG; memcpy(p, "./", 2); p += 2; + tolen -= 2; /* that would be . - just ignore */ break; case 5: - p += udf_get_filename(sb, pc->componentIdent, p, - pc->lengthComponentIdent); + comp_len = udf_get_filename(sb, pc->componentIdent, + pc->lengthComponentIdent, + p, tolen); + p += comp_len; + tolen -= comp_len; + if (tolen == 0) + return -ENAMETOOLONG; *p++ = '/'; + tolen--; break; } elen += sizeof(struct pathComponent) + pc->lengthComponentIdent; @@ -73,6 +91,7 @@ static void udf_pc_to_char(struct super_block *sb, unsigned char *from, p[-1] = '\0'; else p[0] = '\0'; + return 0; } static int udf_symlink_filler(struct file *file, struct page *page) @@ -108,8 +127,10 @@ static int udf_symlink_filler(struct file *file, struct page *page) symlink = bh->b_data; } - udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p); + err = udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p, PAGE_SIZE); brelse(bh); + if (err) + goto out_unlock_inode; up_read(&iinfo->i_data_sem); SetPageUptodate(page); -- cgit v1.2.3-58-ga151