Linux: >> Linux Kernel >> 6.1.124 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Check BIOS images before it is used
BIOS images may fail to load and null checks are added before they are
used.
This fixes 6 NULL_RETURNS issues reported by Coverity.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-09-27
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Check denominator crb_pipes before used
[WHAT & HOW]
A denominator cannot be 0, and is checked before used.
This fixes 2 DIVIDE_BY_ZERO issues reported by Coverity.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-09-18
In the Linux kernel, the following vulnerability has been resolved:
powerpc/rtas: Prevent Spectre v1 gadget construction in sys_rtas()
Smatch warns:
arch/powerpc/kernel/rtas.c:1932 __do_sys_rtas() warn: potential
spectre issue 'args.args' [r] (local cap)
The 'nargs' and 'nret' locals come directly from a user-supplied
buffer and are used as indexes into a small stack-based array and as
inputs to copy_to_user() after they are subject to bounds checks.
Use array_index_nospec() after the bounds checks to clamp these values
for speculative execution.
CVSS Score
7.1
EPSS Score
0.0
Published
2024-09-18
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Validate function returns
[WHAT & HOW]
Function return values must be checked before data can be used
in subsequent functions.
This fixes 4 CHECKED_RETURN issues reported by Coverity.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-09-18
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Run DC_LOG_DC after checking link->link_enc
[WHAT]
The DC_LOG_DC should be run after link->link_enc is checked, not before.
This fixes 1 REVERSE_INULL issue reported by Coverity.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-09-18
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Check UnboundedRequestEnabled's value
CalculateSwathAndDETConfiguration_params_st's UnboundedRequestEnabled
is a pointer (i.e. dml_bool_t *UnboundedRequestEnabled), and thus
if (p->UnboundedRequestEnabled) checks its address, not bool value.
This fixes 1 REVERSE_INULL issue reported by Coverity.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-09-18
In the Linux kernel, the following vulnerability has been resolved:
fscache: delete fscache_cookie_lru_timer when fscache exits to avoid UAF
The fscache_cookie_lru_timer is initialized when the fscache module
is inserted, but is not deleted when the fscache module is removed.
If timer_reduce() is called before removing the fscache module,
the fscache_cookie_lru_timer will be added to the timer list of
the current cpu. Afterwards, a use-after-free will be triggered
in the softIRQ after removing the fscache module, as follows:
==================================================================
BUG: unable to handle page fault for address: fffffbfff803c9e9
PF: supervisor read access in kernel mode
PF: error_code(0x0000) - not-present page
PGD 21ffea067 P4D 21ffea067 PUD 21ffe6067 PMD 110a7c067 PTE 0
Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G W 6.11.0-rc3 #855
Tainted: [W]=WARN
RIP: 0010:__run_timer_base.part.0+0x254/0x8a0
Call Trace:
<IRQ>
tmigr_handle_remote_up+0x627/0x810
__walk_groups.isra.0+0x47/0x140
tmigr_handle_remote+0x1fa/0x2f0
handle_softirqs+0x180/0x590
irq_exit_rcu+0x84/0xb0
sysvec_apic_timer_interrupt+0x6e/0x90
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:default_idle+0xf/0x20
default_idle_call+0x38/0x60
do_idle+0x2b5/0x300
cpu_startup_entry+0x54/0x60
start_secondary+0x20d/0x280
common_startup_64+0x13e/0x148
</TASK>
Modules linked in: [last unloaded: netfs]
==================================================================
Therefore delete fscache_cookie_lru_timer when removing the fscahe module.
CVSS Score
7.8
EPSS Score
0.0
Published
2024-09-18
In the Linux kernel, the following vulnerability has been resolved:
userfaultfd: fix checks for huge PMDs
Patch series "userfaultfd: fix races around pmd_trans_huge() check", v2.
The pmd_trans_huge() code in mfill_atomic() is wrong in three different
ways depending on kernel version:
1. The pmd_trans_huge() check is racy and can lead to a BUG_ON() (if you hit
the right two race windows) - I've tested this in a kernel build with
some extra mdelay() calls. See the commit message for a description
of the race scenario.
On older kernels (before 6.5), I think the same bug can even
theoretically lead to accessing transhuge page contents as a page table
if you hit the right 5 narrow race windows (I haven't tested this case).
2. As pointed out by Qi Zheng, pmd_trans_huge() is not sufficient for
detecting PMDs that don't point to page tables.
On older kernels (before 6.5), you'd just have to win a single fairly
wide race to hit this.
I've tested this on 6.1 stable by racing migration (with a mdelay()
patched into try_to_migrate()) against UFFDIO_ZEROPAGE - on my x86
VM, that causes a kernel oops in ptlock_ptr().
3. On newer kernels (>=6.5), for shmem mappings, khugepaged is allowed
to yank page tables out from under us (though I haven't tested that),
so I think the BUG_ON() checks in mfill_atomic() are just wrong.
I decided to write two separate fixes for these (one fix for bugs 1+2, one
fix for bug 3), so that the first fix can be backported to kernels
affected by bugs 1+2.
This patch (of 2):
This fixes two issues.
I discovered that the following race can occur:
mfill_atomic other thread
============ ============
<zap PMD>
pmdp_get_lockless() [reads none pmd]
<bail if trans_huge>
<if none:>
<pagefault creates transhuge zeropage>
__pte_alloc [no-op]
<zap PMD>
<bail if pmd_trans_huge(*dst_pmd)>
BUG_ON(pmd_none(*dst_pmd))
I have experimentally verified this in a kernel with extra mdelay() calls;
the BUG_ON(pmd_none(*dst_pmd)) triggers.
On kernels newer than commit 0d940a9b270b ("mm/pgtable: allow
pte_offset_map[_lock]() to fail"), this can't lead to anything worse than
a BUG_ON(), since the page table access helpers are actually designed to
deal with page tables concurrently disappearing; but on older kernels
(<=6.4), I think we could probably theoretically race past the two
BUG_ON() checks and end up treating a hugepage as a page table.
The second issue is that, as Qi Zheng pointed out, there are other types
of huge PMDs that pmd_trans_huge() can't catch: devmap PMDs and swap PMDs
(in particular, migration PMDs).
On <=6.4, this is worse than the first issue: If mfill_atomic() runs on a
PMD that contains a migration entry (which just requires winning a single,
fairly wide race), it will pass the PMD to pte_offset_map_lock(), which
assumes that the PMD points to a page table.
Breakage follows: First, the kernel tries to take the PTE lock (which will
crash or maybe worse if there is no "struct page" for the address bits in
the migration entry PMD - I think at least on X86 there usually is no
corresponding "struct page" thanks to the PTE inversion mitigation, amd64
looks different).
If that didn't crash, the kernel would next try to write a PTE into what
it wrongly thinks is a page table.
As part of fixing these issues, get rid of the check for pmd_trans_huge()
before __pte_alloc() - that's redundant, we're going to have to check for
that after the __pte_alloc() anyway.
Backport note: pmdp_get_lockless() is pmd_read_atomic() in older kernels.
CVSS Score
4.7
EPSS Score
0.0
Published
2024-09-18
In the Linux kernel, the following vulnerability has been resolved:
btrfs: don't BUG_ON() when 0 reference count at btrfs_lookup_extent_info()
Instead of doing a BUG_ON() handle the error by returning -EUCLEAN,
aborting the transaction and logging an error message.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-09-18
In the Linux kernel, the following vulnerability has been resolved:
btrfs: handle errors from btrfs_dec_ref() properly
In walk_up_proc() we BUG_ON(ret) from btrfs_dec_ref(). This is
incorrect, we have proper error handling here, return the error.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-09-18