Since the len argument value passed to exfat_ioctl_set_volume_label() from exfat_nls_to_utf16() is passed 1 too large, an out-of-bounds read occurs when dereferencing p_cstring in exfat_nls_to_ucs2() later.
And because of the NLS_NAME_OVERLEN macro, another error occurs when creating a file with a period at the end using utf8 and other iocharsets, so the NLS_NAME_OVERLEN macro should be removed and the len argument value should be passed as FSLABEL_MAX - 1.
Cc: stable@vger.kernel.org Reported-by: syzbot+98cc76a76de46b3714d4@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=98cc76a76de46b3714d4 Fixes: 370e812b3ec1 ("exfat: add nls operations") Signed-off-by: Jeongjun Park aha310510@gmail.com --- fs/exfat/file.c | 2 +- fs/exfat/nls.c | 3 --- 2 files changed, 1 insertion(+), 4 deletions(-)
diff --git a/fs/exfat/file.c b/fs/exfat/file.c index f246cf439588..7ce0fb6f2564 100644 --- a/fs/exfat/file.c +++ b/fs/exfat/file.c @@ -521,7 +521,7 @@ static int exfat_ioctl_set_volume_label(struct super_block *sb,
memset(&uniname, 0, sizeof(uniname)); if (label[0]) { - ret = exfat_nls_to_utf16(sb, label, FSLABEL_MAX, + ret = exfat_nls_to_utf16(sb, label, FSLABEL_MAX - 1, &uniname, &lossy); if (ret < 0) return ret; diff --git a/fs/exfat/nls.c b/fs/exfat/nls.c index 8243d94ceaf4..57db08a5271c 100644 --- a/fs/exfat/nls.c +++ b/fs/exfat/nls.c @@ -616,9 +616,6 @@ static int exfat_nls_to_ucs2(struct super_block *sb, unilen++; }
- if (p_cstring[i] != '\0') - lossy |= NLS_NAME_OVERLEN; - *uniname = '\0'; p_uniname->name_len = unilen; p_uniname->name_hash = exfat_calc_chksum16(upname, unilen << 1, 0, --