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fat: fix memory allocation failure handling of match_strdup() 

commit 35033ab988c396ad7bce3b6d24060c16a9066db8 upstream.

In parse_options(), if match_strdup() failed, parse_options() leaves
opts->iocharset in unexpected state (i.e.  still pointing the freed
string).  And this can be the cause of double free.

To fix, this initialize opts->iocharset always when freeing.

Change-Id: Ic7e843b1b4f66cefa10e9563d8a382c29e436099
Link: http://lkml.kernel.org/r/8736wp9dzc.fsf@mail.parknet.co.jp
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Reported-by: syzbot+90b8e10515ae88228a92@syzkaller.appspotmail.com
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
This commit is contained in:
OGAWA Hirofumi 2018-07-20 17:53:42 -07:00 committed by syphyr
parent 4d2a8d77f7
commit 47c76efa3f
1 changed files with 13 additions and 7 deletions
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20
fs/fat/inode.c
View File

@ -548,13 +548,21 @@ static void fat_set_state(struct super_block *sb,
brelse(bh);
}
static void fat_reset_iocharset(struct fat_mount_options *opts)
{
if (opts->iocharset != fat_default_iocharset) {
/* Note: opts->iocharset can be NULL here */
kfree(opts->iocharset);
opts->iocharset = fat_default_iocharset;
}
}
static void delayed_free(struct rcu_head *p)
{
struct msdos_sb_info *sbi = container_of(p, struct msdos_sb_info, rcu);
unload_nls(sbi->nls_disk);
unload_nls(sbi->nls_io);
if (sbi->options.iocharset != fat_default_iocharset)
kfree(sbi->options.iocharset);
fat_reset_iocharset(&sbi->options);
kfree(sbi);
}
@ -972,7 +980,7 @@ static int parse_options(struct super_block *sb, char *options, int is_vfat,
opts->fs_fmask = opts->fs_dmask = current_umask();
opts->allow_utime = -1;
opts->codepage = fat_default_codepage;
opts->iocharset = fat_default_iocharset;
fat_reset_iocharset(opts);
if (is_vfat) {
opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
opts->rodir = 0;
@ -1119,8 +1127,7 @@ static int parse_options(struct super_block *sb, char *options, int is_vfat,
/* vfat specific */
case Opt_charset:
if (opts->iocharset != fat_default_iocharset)
kfree(opts->iocharset);
fat_reset_iocharset(opts);
iocharset = match_strdup(&args[0]);
if (!iocharset)
return -ENOMEM;
@ -1595,8 +1602,7 @@ out_fail:
iput(fat_inode);
unload_nls(sbi->nls_io);
unload_nls(sbi->nls_disk);
if (sbi->options.iocharset != fat_default_iocharset)
kfree(sbi->options.iocharset);
fat_reset_iocharset(&sbi->options);
sb->s_fs_info = NULL;
kfree(sbi);
return error;