On 2024/6/29 11:31, Pei Li wrote: > Specify the size of s_volume_name in strscpy_pad() to avoid buffer > overflow. > > Reported-by: syzbot+2cab87506a0e7885f4b9@xxxxxxxxxxxxxxxxxxxxxxxxx > Closes: https://syzkaller.appspot.com/bug?extid=2cab87506a0e7885f4b9 Please add, Fixes: 744a56389f73 ("ext4: replace deprecated strncpy with alternatives") > Signed-off-by: Pei Li <peili.dev@xxxxxxxxx> > --- > strscpy_pad() by default takes the size of destination string as the > size to be read from source string. However, as s_volume_name is only > declared as an array of size EXT4_LABEL_MAX, we are reading 1 byte more > than expected. > I'd suggested to move this into the commit log to make it easier to understand, and IIUC this issue only happens when s_volume_name is full of 16 bytes length since it's not NULL terminated, so it can't break out after copying 16 bytes. Thanks, Yi. > Specify the size of s_volume_name in strscpy_pad() to avoid buffer > overflow.> --- > fs/ext4/ioctl.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c > index dab7acd49709..0c4fb579757a 100644 > --- a/fs/ext4/ioctl.c > +++ b/fs/ext4/ioctl.c > @@ -1151,7 +1151,7 @@ static int ext4_ioctl_getlabel(struct ext4_sb_info *sbi, char __user *user_label > BUILD_BUG_ON(EXT4_LABEL_MAX >= FSLABEL_MAX); > > lock_buffer(sbi->s_sbh); > - strscpy_pad(label, sbi->s_es->s_volume_name); > + strscpy_pad(label, sbi->s_es->s_volume_name, EXT4_LABEL_MAX); > unlock_buffer(sbi->s_sbh); > > if (copy_to_user(user_label, label, sizeof(label))) > > --- > base-commit: 55027e689933ba2e64f3d245fb1ff185b3e7fc81 > change-id: 20240628-bug8-7f700a228c4a > > Best regards, >
