| Message ID | 20240702-bug8-v2-1-be675f490db1@gmail.com |
|---|---|
| State | Rejected |
| Headers | show |
| Series | [v2] Fix WARNING in __ext4_ioctl | expand |
On 2024/7/3 8:07, Pei Li wrote: > 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@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=2cab87506a0e7885f4b9 > Fixes: 744a56389f73 ("ext4: replace deprecated strncpy with alternatives") > Signed-off-by: Pei Li <peili.dev@gmail.com> Thanks for the fix, it looks good to me. Reviewed-by: Zhang Yi <yi.zhang@huawei.com> > --- > 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@gmail.com > --- > 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, >
Thanks for the patch; however, the correct fix submitted by Kees with
this commit:
commit be27cd64461c45a6088a91a04eba5cd44e1767ef
Author: Kees Cook <kees@kernel.org>
Date: Thu May 23 15:54:12 2024 -0700
ext4: use memtostr_pad() for s_volume_name
As with the other strings in struct ext4_super_block, s_volume_name is
not NUL terminated. The other strings were marked in commit 072ebb3bffe6
("ext4: add nonstring annotations to ext4.h"). Using strscpy() isn't
the right replacement for strncpy(); it should use memtostr_pad()
instead.
Reported-by: syzbot+50835f73143cc2905b9e@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/00000000000019f4c00619192c05@google.com/
Fixes: 744a56389f73 ("ext4: replace deprecated strncpy with alternatives")
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://patch.msgid.link/20240523225408.work.904-kees@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
- Ted
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)))
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@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=2cab87506a0e7885f4b9 Fixes: 744a56389f73 ("ext4: replace deprecated strncpy with alternatives") Signed-off-by: Pei Li <peili.dev@gmail.com> --- 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@gmail.com --- fs/ext4/ioctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- base-commit: 55027e689933ba2e64f3d245fb1ff185b3e7fc81 change-id: 20240628-bug8-7f700a228c4a Best regards,