Date: Thu, 26 Aug 2021 17:36:02 +0800 From: butt3rflyh4ck <butterflyhuangxx@...il.com> To: oss-security@...ts.openwall.com Subject: Re: Linux kernel: fs/btrfs: null-ptr-dereference bug in btrfs_rm_device in fs/btrfs/volumes.c Hi, RedHat has assigned CVE-2021-3739 to this issue. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-3739. Please track the below link for more information. https://bugzilla.redhat.com/show_bug.cgi?id=1997958 Regards, butt3rflyh4ck. On Wed, Aug 25, 2021 at 10:49 AM butt3rflyh4ck <butterflyhuangxx@...il.com> wrote: > > Hello, there is a null pointer dereference bug in the btrfs_rm_device > function in fs/btrfs/volumes.c in linux-5.14.0-rc4+ and reproduce too. > Fortunately, triggering the bug requires ‘CAP_SYS_ADMIN’. > > #Root Cause > When a user invokes a BTRFS_IOC_RM_DEV_V2 ioctl to remove a non-exist > volume device, > it would call btrfs_ioctl_rm_dev_v2 function to implement. And > btrfs_ioctl_rm_dev_v2 would call btrfs_rm_device, > if the id of the volume device is illegal, it would trigger a > null-ptr-deref bug to cause DoS. > > # Analyse > https://lore.kernel.org/linux-btrfs/CAFcO6XO5TC5sEo-C9JGC75JkNAzkOSSLA3a=bwQqXFFbRTZ7Gw@mail.gmail.com/T/#md4b850f33616b7364f86e6fed144abc925f3669c > > #Fix > the patch for this issue, not available upstream now. > https://firstname.lastname@example.org/T/#u > > > #Timeline > *2021/8/6 - Vulnerability reported to maintainer and CC to > linux-btrfs@...r.kernel.org. > *2021/8/6 - Vulnerability confirmed and patched. > *2021/8/10 - Vulnerability reported to secalert@...hat.com. > *2021/8/25 - Opened on oss-security@...ts.openwall.com. > > #Credit > the issue is reported by Active Defense Lab of Venustech. > > Regards, > butt3rflyh4ck. > -- > Active Defense Lab of Venustech -- Active Defense Lab of Venustech
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