Specify the size of s_volume_name in strscpy_pad() to avoid buffer overflow. 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. Reported-by: syzbot+2cab87506a0e7885f4b9@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=2cab87506a0e7885f4b9 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. Specify the size of s_volume_name in strscpy_pad() to avoid buffer overflow. --- Changes in v2: - Add fixes label - Move workaround into commit log - Link to v1: https://lore.kernel.org/r/20240628-bug8-v1-1-417ef53cca33@xxxxxxxxx --- 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, -- Pei Li <peili.dev@xxxxxxxxx>
