In the Linux kernel, the following vulnerability has been resolved:
proc: fix UAF in proc_get_inode()
Fix race between rmmod and /proc/XXX's inode instantiation.
The bug is that pde->proc_ops don't belong to /proc, it belongs to a
module, therefore dereferencing it after /proc entry has been registered
is a bug unless use_pde/unuse_pde() pair has been used.
use_pde/unuse_pde can be avoided (2 atomic ops!) because pde->proc_ops
never changes so information necessary for inode instantiation can be
saved _before_ proc_register() in PDE itself and used later, avoiding
pde->proc_ops->... dereference.
rmmod lookup
sys_delete_module
proc_lookup_de
pde_get(de);
proc_get_inode(dir->i_sb, de);
mod->exit()
proc_remove
remove_proc_subtree
proc_entry_rundown(de);
free_module(mod);
if (S_ISREG(inode->i_mode))
if (de->proc_ops->proc_read_iter)
--> As module is already freed, will trigger UAF
BUG: unable to handle page fault for address: fffffbfff80a702b
PGD 817fc4067 P4D 817fc4067 PUD 817fc0067 PMD 102ef4067 PTE 0
Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 26 UID: 0 PID: 2667 Comm: ls Tainted: G
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
RIP: 0010:proc_get_inode+0x302/0x6e0
RSP: 0018:ffff88811c837998 EFLAGS: 00010a06
RAX: dffffc0000000000 RBX: ffffffffc0538140 RCX: 0000000000000007
RDX: 1ffffffff80a702b RSI: 0000000000000001 RDI: ffffffffc0538158
RBP: ffff8881299a6000 R08: 0000000067bbe1e5 R09: 1ffff11023906f20
R10: ffffffffb560ca07 R11: ffffffffb2b43a58 R12: ffff888105bb78f0
R13: ffff888100518048 R14: ffff8881299a6004 R15: 0000000000000001
FS: 00007f95b9686840(0000) GS:ffff8883af100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffbfff80a702b CR3: 0000000117dd2000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
proc_lookup_de+0x11f/0x2e0
__lookup_slow+0x188/0x350
walk_component+0x2ab/0x4f0
path_lookupat+0x120/0x660
filename_lookup+0x1ce/0x560
vfs_statx+0xac/0x150
__do_sys_newstat+0x96/0x110
do_syscall_64+0x5f/0x170
entry_SYSCALL_64_after_hwframe+0x76/0x7e
[adobriyan@gmail.com: don't do 2 atomic ops on the common path]
In the Linux kernel, the following vulnerability has been resolved:
net: atm: fix use after free in lec_send()
The ->send() operation frees skb so save the length before calling
->send() to avoid a use after free.
In the Linux kernel, the following vulnerability has been resolved:
iscsi_ibft: Fix UBSAN shift-out-of-bounds warning in ibft_attr_show_nic()
When performing an iSCSI boot using IPv6, iscsistart still reads the
/sys/firmware/ibft/ethernetX/subnet-mask entry. Since the IPv6 prefix
length is 64, this causes the shift exponent to become negative,
triggering a UBSAN warning. As the concept of a subnet mask does not
apply to IPv6, the value is set to ~0 to suppress the warning message.
In the Linux kernel, the following vulnerability has been resolved:
scsi: qla1280: Fix kernel oops when debug level > 2
A null dereference or oops exception will eventually occur when qla1280.c
driver is compiled with DEBUG_QLA1280 enabled and ql_debug_level > 2. I
think its clear from the code that the intention here is sg_dma_len(s) not
length of sg_next(s) when printing the debug info.
In the Linux kernel, the following vulnerability has been resolved:
ppp: Fix KMSAN uninit-value warning with bpf
Syzbot caught an "KMSAN: uninit-value" warning [1], which is caused by the
ppp driver not initializing a 2-byte header when using socket filter.
The following code can generate a PPP filter BPF program:
'''
struct bpf_program fp;
pcap_t *handle;
handle = pcap_open_dead(DLT_PPP_PPPD, 65535);
pcap_compile(handle, &fp, "ip and outbound", 0, 0);
bpf_dump(&fp, 1);
'''
Its output is:
'''
(000) ldh [2]
(001) jeq #0x21 jt 2 jf 5
(002) ldb [0]
(003) jeq #0x1 jt 4 jf 5
(004) ret #65535
(005) ret #0
'''
Wen can find similar code at the following link:
https://github.com/ppp-project/ppp/blob/master/pppd/options.c#L1680
The maintainer of this code repository is also the original maintainer
of the ppp driver.
As you can see the BPF program skips 2 bytes of data and then reads the
'Protocol' field to determine if it's an IP packet. Then it read the first
byte of the first 2 bytes to determine the direction.
The issue is that only the first byte indicating direction is initialized
in current ppp driver code while the second byte is not initialized.
For normal BPF programs generated by libpcap, uninitialized data won't be
used, so it's not a problem. However, for carefully crafted BPF programs,
such as those generated by syzkaller [2], which start reading from offset
0, the uninitialized data will be used and caught by KMSAN.
[1] https://syzkaller.appspot.com/bug?extid=853242d9c9917165d791
[2] https://syzkaller.appspot.com/text?tag=ReproC&x=11994913980000
In the Linux kernel, the following vulnerability has been resolved:
cifs: fix potential memory leaks in session setup
Make sure to free cifs_ses::auth_key.response before allocating it as
we might end up leaking memory in reconnect or mounting.
In the Linux kernel, the following vulnerability has been resolved:
x86/i8259: Mark legacy PIC interrupts with IRQ_LEVEL
Baoquan reported that after triggering a crash the subsequent crash-kernel
fails to boot about half of the time. It triggers a NULL pointer
dereference in the periodic tick code.
This happens because the legacy timer interrupt (IRQ0) is resent in
software which happens in soft interrupt (tasklet) context. In this context
get_irq_regs() returns NULL which leads to the NULL pointer dereference.
The reason for the resend is a spurious APIC interrupt on the IRQ0 vector
which is captured and leads to a resend when the legacy timer interrupt is
enabled. This is wrong because the legacy PIC interrupts are level
triggered and therefore should never be resent in software, but nothing
ever sets the IRQ_LEVEL flag on those interrupts, so the core code does not
know about their trigger type.
Ensure that IRQ_LEVEL is set when the legacy PCI interrupts are set up.