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authorOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>2018-07-21 03:53:42 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2018-07-21 22:50:46 +0300
commit35033ab988c396ad7bce3b6d24060c16a9066db8 (patch)
tree52602d1e8977c4fa765150c99f9af610f7a8fe5e /fs/fat
parent5a6964944cdfe83de849a5f748f51c983f9914ec (diff)
downloadlinux-35033ab988c396ad7bce3b6d24060c16a9066db8.tar.xz
fat: fix memory allocation failure handling of match_strdup()
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. 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 Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/fat')
-rw-r--r--fs/fat/inode.c20
1 files changed, 13 insertions, 7 deletions
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 065dc919a0ce..bfd589ea74c0 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -707,13 +707,21 @@ 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);
}
@@ -1132,7 +1140,7 @@ 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;
@@ -1289,8 +1297,7 @@ 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;
@@ -1881,8 +1888,7 @@ 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;