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 <chlunde@ping.uio.no>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/udf/dir.c b/fs/udf/dir.c
index a012c51caffd2a195b6015b9594d0f1862dba324..a7690b46ce0a18624b80f056b1399c9520dffeda 100644 (file)
--- a/fs/udf/dir.c
+++ b/fs/udf/dir.c
@@ -167,7 +167,8 @@ static int udf_readdir(struct file *file, struct dir_context *ctx)
                        continue;
                }
 
-               flen = udf_get_filename(dir->i_sb, nameptr, fname, lfi);
+               flen = udf_get_filename(dir->i_sb, nameptr, lfi, fname,
+                                       UDF_NAME_LEN);
                if (!flen)
                        continue;
 

diff --git a/fs/udf/namei.c b/fs/udf/namei.c
index c12e260fd6c417eb9c690782b8860f0e5eeff8d9..6ff19b54b51f285971232e30e9d437fa3966654a 100644 (file)
--- a/fs/udf/namei.c
+++ b/fs/udf/namei.c
@@ -233,7 +233,8 @@ static struct fileIdentDesc *udf_find_entry(struct inode *dir,
                if (!lfi)
                        continue;
 
-               flen = udf_get_filename(dir->i_sb, nameptr, fname, lfi);
+               flen = udf_get_filename(dir->i_sb, nameptr, lfi, fname,
+                                       UDF_NAME_LEN);
                if (flen && udf_match(flen, fname, child->len, child->name))
                        goto out_ok;
        }

diff --git a/fs/udf/symlink.c b/fs/udf/symlink.c
index c3aa6fafd6cf695960a44dd2737ff5c62fb21d4a..0f1b3a2654b9459a36c4df943f1f22a3bff070af 100644 (file)
--- a/fs/udf/symlink.c
+++ b/fs/udf/symlink.c
@@ -30,13 +30,16 @@
 #include <linux/buffer_head.h>
 #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);

diff --git a/fs/udf/udfdecl.h b/fs/udf/udfdecl.h
index 1cc3c993ebd04f4adb7b425f500e40d1185aae9f..47bb3f5ca360d4f1be8f92036685278868ab99e3 100644 (file)
--- a/fs/udf/udfdecl.h
+++ b/fs/udf/udfdecl.h
@@ -211,7 +211,8 @@ udf_get_lb_pblock(struct super_block *sb, struct kernel_lb_addr *loc,
 }
 
 /* unicode.c */
-extern int udf_get_filename(struct super_block *, uint8_t *, uint8_t *, int);
+extern int udf_get_filename(struct super_block *, uint8_t *, int, uint8_t *,
+                           int);
 extern int udf_put_filename(struct super_block *, const uint8_t *, uint8_t *,
                            int);
 extern int udf_build_ustr(struct ustr *, dstring *, int);

diff --git a/fs/udf/unicode.c b/fs/udf/unicode.c
index afd470e588ffbbd24ec886b3e8a619833a5e3e9a..b84fee372734bd494ba5eb86f5ce5c8c28b99b5a 100644 (file)
--- a/fs/udf/unicode.c
+++ b/fs/udf/unicode.c
@@ -28,7 +28,8 @@
 
 #include "udf_sb.h"
 
-static int udf_translate_to_linux(uint8_t *, uint8_t *, int, uint8_t *, int);
+static int udf_translate_to_linux(uint8_t *, int, uint8_t *, int, uint8_t *,
+                                 int);
 
 static int udf_char_to_ustr(struct ustr *dest, const uint8_t *src, int strlen)
 {
@@ -333,8 +334,8 @@ try_again:
        return u_len + 1;
 }
 
-int udf_get_filename(struct super_block *sb, uint8_t *sname, uint8_t *dname,
-                    int flen)
+int udf_get_filename(struct super_block *sb, uint8_t *sname, int slen,
+                    uint8_t *dname, int dlen)
 {
        struct ustr *filename, *unifilename;
        int len = 0;
@@ -347,7 +348,7 @@ int udf_get_filename(struct super_block *sb, uint8_t *sname, uint8_t *dname,
        if (!unifilename)
                goto out1;
 
-       if (udf_build_ustr_exact(unifilename, sname, flen))
+       if (udf_build_ustr_exact(unifilename, sname, slen))
                goto out2;
 
        if (UDF_QUERY_FLAG(sb, UDF_FLAG_UTF8)) {
@@ -366,7 +367,8 @@ int udf_get_filename(struct super_block *sb, uint8_t *sname, uint8_t *dname,
        } else
                goto out2;
 
-       len = udf_translate_to_linux(dname, filename->u_name, filename->u_len,
+       len = udf_translate_to_linux(dname, dlen,
+                                    filename->u_name, filename->u_len,
                                     unifilename->u_name, unifilename->u_len);
 out2:
        kfree(unifilename);
@@ -403,10 +405,12 @@ int udf_put_filename(struct super_block *sb, const uint8_t *sname,
 #define EXT_MARK               '.'
 #define CRC_MARK               '#'
 #define EXT_SIZE               5
+/* Number of chars we need to store generated CRC to make filename unique */
+#define CRC_LEN                        5
 
-static int udf_translate_to_linux(uint8_t *newName, uint8_t *udfName,
-                                 int udfLen, uint8_t *fidName,
-                                 int fidNameLen)
+static int udf_translate_to_linux(uint8_t *newName, int newLen,
+                                 uint8_t *udfName, int udfLen,
+                                 uint8_t *fidName, int fidNameLen)
 {
        int index, newIndex = 0, needsCRC = 0;
        int extIndex = 0, newExtIndex = 0, hasExt = 0;
@@ -439,7 +443,7 @@ static int udf_translate_to_linux(uint8_t *newName, uint8_t *udfName,
                                        newExtIndex = newIndex;
                                }
                        }
-                       if (newIndex < 256)
+                       if (newIndex < newLen)
                                newName[newIndex++] = curr;
                        else
                                needsCRC = 1;
@@ -467,13 +471,13 @@ static int udf_translate_to_linux(uint8_t *newName, uint8_t *udfName,
                                }
                                ext[localExtIndex++] = curr;
                        }
-                       maxFilenameLen = 250 - localExtIndex;
+                       maxFilenameLen = newLen - CRC_LEN - localExtIndex;
                        if (newIndex > maxFilenameLen)
                                newIndex = maxFilenameLen;
                        else
                                newIndex = newExtIndex;
-               } else if (newIndex > 250)
-                       newIndex = 250;
+               } else if (newIndex > newLen - CRC_LEN)
+                       newIndex = newLen - CRC_LEN;
                newName[newIndex++] = CRC_MARK;
                valueCRC = crc_itu_t(0, fidName, fidNameLen);
                newName[newIndex++] = hex_asc_upper_hi(valueCRC >> 8);