CVE-2026-64451— tracing: Fix NULL pointer dereference in func_set_flag()
Quick assessment
Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于func_set_flag()函数在验证当前跟踪器是否为函数跟踪器之前无条件取消引用tr->current_trace_flags，导致空指针取消引用和内核崩溃。
Possible ATT&CK Techniques 1 AI
T1059 · Command and Scripting InterpreterAffected Version Matrix 6
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| Linux | Linux | 76680d0d2825900f23bf35290ab2b80bdf3a8e4a< 69f17ac132a38974cf1defb480cef6b79d1ab768 |
affected |
76680d0d2825900f23bf35290ab2b80bdf3a8e4a< c3e94604675e3db186111b8942650d86577df9b0 |
affected | ||
6.19 |
affected | ||
< 6.19 |
unaffected | ||
7.1.4≤ 7.1.* |
unaffected | ||
7.2≤ * |
unaffected |
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I. Basic Information for CVE-2026-64451
Vulnerability Information
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Vulnerability Title
tracing: Fix NULL pointer dereference in func_set_flag()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
tracing: Fix NULL pointer dereference in func_set_flag()
func_set_flag() dereferences tr->current_trace_flags before verifying
that the current tracer is actually the function tracer. When the active
tracer has been switched away from "function" (e.g., to "wakeup_rt"),
tr->current_trace_flags can be NULL, leading to a NULL pointer
dereference and kernel crash.
The call chain that triggers this is:
trace_options_write()
-> __set_tracer_option()
-> trace->set_flag() /* func_set_flag */
In func_set_flag(), the first operation is:
if (!!set == !!(tr->current_trace_flags->val & bit))
This dereferences tr->current_trace_flags unconditionally. The safety
check that guards against a non-function tracer:
if (tr->current_trace != &function_trace)
return 0;
is placed *after* the dereference, which is too late.
This was observed with the following crash dump:
BUG: unable to handle page fault at 0000000000000000
RIP: func_set_flag+0xd
Call Trace:
__set_tracer_option+0x27
trace_options_write+0x75
vfs_write+0x12a
ksys_write+0x66
do_syscall_64+0x5b
RIP: ffffffff914c973d RSP: ff67ec88b01dfdf0 RFLAGS: 00010202
RAX: 0000000000000000 RBX: ff3a826e80354580 RCX: 0000000000000001
RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffffff93918080
The disassembly confirms the fault:
func_set_flag+0: mov 0x1f08(%rdi), %rax ; RAX = tr->current_trace_flags = NULL
func_set_flag+13: mov (%rax), %eax ; page fault: dereference NULL
At the time of the crash:
tr->current_trace_flags = 0x0 (NULL)
tr->current_trace = wakeup_rt_tracer (not function_trace)
The scenario is that a process opens a function tracer option file (such
as "func_stack_trace"), then the current tracer is switched to another
tracer (e.g., "wakeup_rt"), which sets current_trace_flags to NULL. When
the process subsequently writes to the option file, func_set_flag() is
invoked and crashes on the NULL dereference.
Fix this by moving the current_trace check before the
current_trace_flags dereference, so that func_set_flag() returns early
when the function tracer is not active.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于func_set_flag()函数在验证当前跟踪器是否为函数跟踪器之前无条件取消引用tr->current_trace_flags，导致空指针取消引用和内核崩溃。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2026-64451
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|---|
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Patches & Fixes for CVE-2026-64451 (2)
Same Patch Batch · Linux · 2026-07-25 · 274 CVEs total
| CVE-2026-64355 | 9.8 CRITICAL | bpf: Reject fragmented frames in devmap |
| CVE-2026-64459 | 9.8 CRITICAL | tcp: restore RCU grace period in tcp_ao_destroy_sock |
| CVE-2026-64303 | 9.8 CRITICAL | spi: fsl-lpspi: terminate the RX channel on TX prepare failure path |
| CVE-2026-64439 | 9.8 CRITICAL | crypto: krb5 - filter out async aead implementations at alloc |
| CVE-2026-64410 | 9.8 CRITICAL | netfilter: flowtable: IPIP tunnel hardware offload is not yet support |
| CVE-2026-64399 | 9.8 CRITICAL | ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE |
| CVE-2026-64397 | 9.8 CRITICAL | ksmbd: serialize QUERY_DIRECTORY requests per file |
| CVE-2026-64391 | 9.8 CRITICAL | ksmbd: use opener credentials for ADS I/O |
| CVE-2026-64387 | 9.8 CRITICAL | smb: client: fix query directory replay double-free |
| CVE-2026-64386 | 9.8 CRITICAL | smb: client: fix query_info() replay double-free |
| CVE-2026-64385 | 9.8 CRITICAL | smb: client: fix double-free in SMB2_ioctl() replay |
| CVE-2026-64383 | 9.8 CRITICAL | smb: client: fix double-free in SMB2_flush() replay |
| CVE-2026-64384 | 9.8 CRITICAL | smb: client: fix change notify replay double-free |
| CVE-2026-64268 | 9.8 CRITICAL | RDMA/siw: bound Read Response placement to the RREAD length |
| CVE-2026-64523 | 9.8 CRITICAL | net/handshake: Take a long-lived file reference at submit |
| CVE-2026-64269 | 9.1 CRITICAL | RDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg |
| CVE-2026-64257 | 9.1 CRITICAL | smb: client: reject overlapping data areas in SMB2 responses |
| CVE-2026-64319 | 9.1 CRITICAL | nvmet-auth: validate reply message payload bounds against transfer length |
| CVE-2026-64320 | 9.1 CRITICAL | nvmet: fix pre-auth out-of-bounds heap read in Discovery Get Log Page |
| CVE-2026-64393 | 9.1 CRITICAL | ksmbd: run set info with opener credentials |
Showing top 20 of 274 CVEs. View all on vendor page → →
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Same vendor: Linux
-
CVE-2026-99999
ipv4: validate checksum_start before completing checksum -
CVE-2026-98432
ipv4: free inet_opt and ireq_opt after an RCU grace period -
CVE-2026-98431
RDMA/uverbs: Fix mmap_lock/disassociation_lock circular depe -
CVE-2026-98430
RDMA/efa: Keep admin queues alive while IRQ is registered -
CVE-2026-98429
RDMA/efa: Keep EQ resources alive while IRQ is registered
V. Comments for CVE-2026-64451
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