Linux: >> Linux Kernel >> 5.4.172 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix pointer-leak due to insufficient speculative store bypass mitigation
To mitigate Spectre v4, 2039f26f3aca ("bpf: Fix leakage due to
insufficient speculative store bypass mitigation") inserts lfence
instructions after 1) initializing a stack slot and 2) spilling a
pointer to the stack.
However, this does not cover cases where a stack slot is first
initialized with a pointer (subject to sanitization) but then
overwritten with a scalar (not subject to sanitization because
the slot was already initialized). In this case, the second write
may be subject to speculative store bypass (SSB) creating a
speculative pointer-as-scalar type confusion. This allows the
program to subsequently leak the numerical pointer value using,
for example, a branch-based cache side channel.
To fix this, also sanitize scalars if they write a stack slot
that previously contained a pointer. Assuming that pointer-spills
are only generated by LLVM on register-pressure, the performance
impact on most real-world BPF programs should be small.
The following unprivileged BPF bytecode drafts a minimal exploit
and the mitigation:
[...]
// r6 = 0 or 1 (skalar, unknown user input)
// r7 = accessible ptr for side channel
// r10 = frame pointer (fp), to be leaked
//
r9 = r10 # fp alias to encourage ssb
*(u64 *)(r9 - 8) = r10 // fp[-8] = ptr, to be leaked
// lfence added here because of pointer spill to stack.
//
// Ommitted: Dummy bpf_ringbuf_output() here to train alias predictor
// for no r9-r10 dependency.
//
*(u64 *)(r10 - 8) = r6 // fp[-8] = scalar, overwrites ptr
// 2039f26f3aca: no lfence added because stack slot was not STACK_INVALID,
// store may be subject to SSB
//
// fix: also add an lfence when the slot contained a ptr
//
r8 = *(u64 *)(r9 - 8)
// r8 = architecturally a scalar, speculatively a ptr
//
// leak ptr using branch-based cache side channel:
r8 &= 1 // choose bit to leak
if r8 == 0 goto SLOW // no mispredict
// architecturally dead code if input r6 is 0,
// only executes speculatively iff ptr bit is 1
r8 = *(u64 *)(r7 + 0) # encode bit in cache (0: slow, 1: fast)
SLOW:
[...]
After running this, the program can time the access to *(r7 + 0) to
determine whether the chosen pointer bit was 0 or 1. Repeat this 64
times to recover the whole address on amd64.
In summary, sanitization can only be skipped if one scalar is
overwritten with another scalar. Scalar-confusion due to speculative
store bypass can not lead to invalid accesses because the pointer
bounds deducted during verification are enforced using branchless
logic. See 979d63d50c0c ("bpf: prevent out of bounds speculation on
pointer arithmetic") for details.
Do not make the mitigation depend on !env->allow_{uninit_stack,ptr_leaks}
because speculative leaks are likely unexpected if these were enabled.
For example, leaking the address to a protected log file may be acceptable
while disabling the mitigation might unintentionally leak the address
into the cached-state of a map that is accessible to unprivileged
processes.
CVSS Score
7.1
EPSS Score
0.0
Published
2025-03-27
In the Linux kernel, the following vulnerability has been resolved:
bnxt: Do not read past the end of test names
Test names were being concatenated based on a offset beyond the end of
the first name, which tripped the buffer overflow detection logic:
detected buffer overflow in strnlen
[...]
Call Trace:
bnxt_ethtool_init.cold+0x18/0x18
Refactor struct hwrm_selftest_qlist_output to use an actual array,
and adjust the concatenation to use snprintf() rather than a series of
strncat() calls.
CVSS Score
5.5
EPSS Score
0.001
Published
2025-03-27
In the Linux kernel, the following vulnerability has been resolved:
HID: betop: check shape of output reports
betopff_init() only checks the total sum of the report counts for each
report field to be at least 4, but hid_betopff_play() expects 4 report
fields.
A device advertising an output report with one field and 4 report counts
would pass the check but crash the kernel with a NULL pointer dereference
in hid_betopff_play().
CVSS Score
5.5
EPSS Score
0.001
Published
2025-03-27
In the Linux kernel, the following vulnerability has been resolved:
EDAC/qcom: Do not pass llcc_driv_data as edac_device_ctl_info's pvt_info
The memory for llcc_driv_data is allocated by the LLCC driver. But when
it is passed as the private driver info to the EDAC core, it will get freed
during the qcom_edac driver release. So when the qcom_edac driver gets probed
again, it will try to use the freed data leading to the use-after-free bug.
Hence, do not pass llcc_driv_data as pvt_info but rather reference it
using the platform_data pointer in the qcom_edac driver.
CVSS Score
7.8
EPSS Score
0.001
Published
2025-03-27
In the Linux kernel, the following vulnerability has been resolved:
trace_events_hist: add check for return value of 'create_hist_field'
Function 'create_hist_field' is called recursively at
trace_events_hist.c:1954 and can return NULL-value that's why we have
to check it to avoid null pointer dereference.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-03-27
In the Linux kernel, the following vulnerability has been resolved:
cifs: Fix oops due to uncleared server->smbd_conn in reconnect
In smbd_destroy(), clear the server->smbd_conn pointer after freeing the
smbd_connection struct that it points to so that reconnection doesn't get
confused.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-03-27
In the Linux kernel, the following vulnerability has been resolved:
tracing: Make sure trace_printk() can output as soon as it can be used
Currently trace_printk() can be used as soon as early_trace_init() is
called from start_kernel(). But if a crash happens, and
"ftrace_dump_on_oops" is set on the kernel command line, all you get will
be:
[ 0.456075] <idle>-0 0dN.2. 347519us : Unknown type 6
[ 0.456075] <idle>-0 0dN.2. 353141us : Unknown type 6
[ 0.456075] <idle>-0 0dN.2. 358684us : Unknown type 6
This is because the trace_printk() event (type 6) hasn't been registered
yet. That gets done via an early_initcall(), which may be early, but not
early enough.
Instead of registering the trace_printk() event (and other ftrace events,
which are not trace events) via an early_initcall(), have them registered at
the same time that trace_printk() can be used. This way, if there is a
crash before early_initcall(), then the trace_printk()s will actually be
useful.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-03-27
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.
CVSS Score
5.5
EPSS Score
0.001
Published
2025-03-27
In the Linux kernel, the following vulnerability has been resolved:
ipv4: prevent potential spectre v1 gadget in fib_metrics_match()
if (!type)
continue;
if (type > RTAX_MAX)
return false;
...
fi_val = fi->fib_metrics->metrics[type - 1];
@type being used as an array index, we need to prevent
cpu speculation or risk leaking kernel memory content.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-03-27
In the Linux kernel, the following vulnerability has been resolved:
ipv4: prevent potential spectre v1 gadget in ip_metrics_convert()
if (!type)
continue;
if (type > RTAX_MAX)
return -EINVAL;
...
metrics[type - 1] = val;
@type being used as an array index, we need to prevent
cpu speculation or risk leaking kernel memory content.
CVSS Score
5.5
EPSS Score
0.001
Published
2025-03-27