linux-stable.git/lib, branch v6.12.86

lib: test_hmm: evict device pages on file close to avoid use-after-free

2026-05-07T04:09:43+00:00

[ Upstream commit 744dd97752ef1076a8d8672bb0d8aa2c7abc1144 ]

Patch series "Minor hmm_test fixes and cleanups".

Two bugfixes a cleanup for the HMM kernel selftests.  These were mostly
reported by Zenghui Yu with special thanks to Lorenzo for analysing and
pointing out the problems.

This patch (of 3):

When dmirror_fops_release() is called it frees the dmirror struct but
doesn't migrate device private pages back to system memory first.  This
leaves those pages with a dangling zone_device_data pointer to the freed
dmirror.

If a subsequent fault occurs on those pages (eg.  during coredump) the
dmirror_devmem_fault() callback dereferences the stale pointer causing a
kernel panic.  This was reported [1] when running mm/ksft_hmm.sh on arm64,
where a test failure triggered SIGABRT and the resulting coredump walked
the VMAs faulting in the stale device private pages.

Fix this by calling dmirror_device_evict_chunk() for each devmem chunk in
dmirror_fops_release() to migrate all device private pages back to system
memory before freeing the dmirror struct.  The function is moved earlier
in the file to avoid a forward declaration.

Link: https://lore.kernel.org/20260331063445.3551404-1-apopple@nvidia.com
Link: https://lore.kernel.org/20260331063445.3551404-2-apopple@nvidia.com
Fixes: b2ef9f5a5cb3 ("mm/hmm/test: add selftest driver for HMM")
Signed-off-by: Alistair Popple 
Reported-by: Zenghui Yu 
Closes: https://lore.kernel.org/linux-mm/8bd0396a-8997-4d2e-a13f-5aac033083d7@linux.dev/
Reviewed-by: Balbir Singh 
Tested-by: Zenghui Yu 
Cc: David Hildenbrand 
Cc: Jason Gunthorpe 
Cc: Leon Romanovsky 
Cc: Liam Howlett 
Cc: Lorenzo Stoakes (Oracle) 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Suren Baghdasaryan 
Cc: Zenghui Yu 
Cc: Matthew Brost 
Cc: 
Signed-off-by: Andrew Morton 
[ kept the existing simpler `dmirror_device_evict_chunk()` body instead of the upstream compound-folio version ]
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

lib/ts_kmp: fix integer overflow in pattern length calculation

2026-05-07T04:09:28+00:00

commit 8cdf30813ea8ce881cecc08664144416dbdb3e16 upstream.

The ts_kmp algorithm stores its prefix_tbl[] table and pattern in a single
allocation sized from the pattern length.  If the prefix_tbl[] size
calculation wraps, the resulting allocation can be too small and
subsequent pattern copies can overflow it.

Fix this by rejecting zero-length patterns and by using overflow helpers
before calculating the combined allocation size.


This fixes a potential heap overflow.  The pattern length calculation can
wrap during a size_t addition, leading to an undersized allocation.
Because the textsearch library is reachable from userspace via Netfilter's
xt_string module, this is a security risk that should be backported to LTS
kernels.

Link: https://lkml.kernel.org/r/20260308202028.2889285-2-objecting@objecting.org
Signed-off-by: Josh Law 
Reviewed-by: Andrew Morton 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

x86-64/arm64/powerpc: clean up and rename __copy_from_user_flushcache

2026-04-22T11:19:02+00:00

commit 809b997a5ce945ab470f70c187048fe4f5df20bf upstream.

This finishes the work on these odd functions that were only implemented
by a handful of architectures.

The 'flushcache' function was only used from the iterator code, and
let's make it do the same thing that the nontemporal version does:
remove the two underscores and add the user address checking.

Yes, yes, the user address checking is also done at iovec import time,
but we have long since walked away from the old double-underscore thing
where we try to avoid address checking overhead at access time, and
these functions shouldn't be so special and old-fashioned.

The arm64 version already did the address check, in fact, so there it's
just a matter of renaming it.  For powerpc and x86-64 we now do the
proper user access boilerplate.

Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

x86: rename and clean up __copy_from_user_inatomic_nocache()

2026-04-22T11:19:02+00:00

commit 5de7bcaadf160c1716b20a263cf8f5b06f658959 upstream.

Similarly to the previous commit, this renames the somewhat confusingly
named function.  But in this case, it was at least less confusing: the
__copy_from_user_inatomic_nocache is indeed copying from user memory,
and it is indeed ok to be used in an atomic context, so it will not warn
about it.

But the previous commit also removed the NTB mis-use of the
__copy_from_user_inatomic_nocache() function, and as a result every
call-site is now _actually_ doing a real user copy.  That means that we
can now do the proper user pointer verification too.

End result: add proper address checking, remove the double underscores,
and change the "nocache" to "nontemporal" to more accurately describe
what this x86-only function actually does.  It might be worth noting
that only the target is non-temporal: the actual user accesses are
normal memory accesses.

Also worth noting is that non-x86 targets (and on older 32-bit x86 CPU's
before XMM2 in the Pentium III) we end up just falling back on a regular
user copy, so nothing can actually depend on the non-temporal semantics,
but that has always been true.

Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

lib/crypto: chacha: Zeroize permuted_state before it leaves scope

2026-04-18T08:41:54+00:00

commit e5046823f8fa3677341b541a25af2fcb99a5b1e0 upstream.

Since the ChaCha permutation is invertible, the local variable
'permuted_state' is sufficient to compute the original 'state', and thus
the key, even after the permutation has been done.

While the kernel is quite inconsistent about zeroizing secrets on the
stack (and some prominent userspace crypto libraries don't bother at all
since it's not guaranteed to work anyway), the kernel does try to do it
as a best practice, especially in cases involving the RNG.

Thus, explicitly zeroize 'permuted_state' before it goes out of scope.

Fixes: c08d0e647305 ("crypto: chacha20 - Add a generic ChaCha20 stream cipher implementation")
Cc: stable@vger.kernel.org
Acked-by: Ard Biesheuvel 
Link: https://lore.kernel.org/r/20260326032920.39408-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers 
Signed-off-by: Greg Kroah-Hartman

lib/bootconfig: check xbc_init_node() return in override path

2026-03-25T10:08:57+00:00

[ Upstream commit bb288d7d869e86d382f35a0e26242c5ccb05ca82 ]

The ':=' override path in xbc_parse_kv() calls xbc_init_node() to
re-initialize an existing value node but does not check the return
value. If xbc_init_node() fails (data offset out of range), parsing
silently continues with stale node data.

Add the missing error check to match the xbc_add_node() call path
which already checks for failure.

In practice, a bootconfig using ':=' to override a value near the
32KB data limit could silently retain the old value, meaning a
security-relevant boot parameter override (e.g., a trace filter or
debug setting) would not take effect as intended.

Link: https://lore.kernel.org/all/20260318155847.78065-2-objecting@objecting.org/

Fixes: e5efaeb8a8f5 ("bootconfig: Support mixing a value and subkeys under a key")
Signed-off-by: Josh Law 
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Sasha Levin

lib/bootconfig: check bounds before writing in __xbc_open_brace()

2026-03-25T10:08:38+00:00

commit 560f763baa0f2c9a44da4294c06af071405ac46f upstream.

The bounds check for brace_index happens after the array write.
While the current call pattern prevents an actual out-of-bounds
access (the previous call would have returned an error), the
write-before-check pattern is fragile and would become a real
out-of-bounds write if the error return were ever not propagated.

Move the bounds check before the array write so the function is
self-contained and safe regardless of caller behavior.

Link: https://lore.kernel.org/all/20260312191143.28719-3-objecting@objecting.org/

Fixes: ead1e19ad905 ("lib/bootconfig: Fix a bug of breaking existing tree nodes")
Cc: stable@vger.kernel.org
Signed-off-by: Josh Law 
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

lib/bootconfig: fix snprintf truncation check in xbc_node_compose_key_after()

2026-03-25T10:08:38+00:00

commit 1120a36bb1e9b9e22de75ecb4ef0b998f73a97f1 upstream.

snprintf() returns the number of characters that would have been
written excluding the NUL terminator.  Output is truncated when the
return value is >= the buffer size, not just > the buffer size.

When ret == size, the current code takes the non-truncated path,
advancing buf by ret and reducing size to 0.  This is wrong because
the output was actually truncated (the last character was replaced by
NUL).  Fix by using >= so the truncation path is taken correctly.

Link: https://lore.kernel.org/all/20260312191143.28719-4-objecting@objecting.org/

Fixes: 76db5a27a827 ("bootconfig: Add Extra Boot Config support")
Cc: stable@vger.kernel.org
Signed-off-by: Josh Law 
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

lib/bootconfig: fix off-by-one in xbc_verify_tree() unclosed brace error

2026-03-25T10:08:38+00:00

commit 39ebc8d7f561e1b64eca87353ef9b18e2825e591 upstream.

__xbc_open_brace() pushes entries with post-increment
(open_brace[brace_index++]), so brace_index always points one past
the last valid entry.  xbc_verify_tree() reads open_brace[brace_index]
to report which brace is unclosed, but this is one past the last
pushed entry and contains stale/zero data, causing the error message
to reference the wrong node.

Use open_brace[brace_index - 1] to correctly identify the unclosed
brace.  brace_index is known to be > 0 here since we are inside the
if (brace_index) guard.

Link: https://lore.kernel.org/all/20260312191143.28719-2-objecting@objecting.org/

Fixes: ead1e19ad905 ("lib/bootconfig: Fix a bug of breaking existing tree nodes")
Cc: stable@vger.kernel.org
Signed-off-by: Josh Law 
Reviewed-by: Steven Rostedt (Google) 
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

Remove WARN_ALL_UNSEEDED_RANDOM kernel config option

2026-03-04T12:21:32+00:00

[ Upstream commit 7dff99b354601dd01829e1511711846e04340a69 ]

This config option goes way back - it used to be an internal debug
option to random.c (at that point called DEBUG_RANDOM_BOOT), then was
renamed and exposed as a config option as CONFIG_WARN_UNSEEDED_RANDOM,
and then further renamed to the current CONFIG_WARN_ALL_UNSEEDED_RANDOM.

It was all done with the best of intentions: the more limited
rate-limited reports were reporting some cases, but if you wanted to see
all the gory details, you'd enable this "ALL" option.

However, it turns out - perhaps not surprisingly - that when people
don't care about and fix the first rate-limited cases, they most
certainly don't care about any others either, and so warning about all
of them isn't actually helping anything.

And the non-ratelimited reporting causes problems, where well-meaning
people enable debug options, but the excessive flood of messages that
nobody cares about will hide actual real information when things go
wrong.

I just got a kernel bug report (which had nothing to do with randomness)
where two thirds of the the truncated dmesg was just variations of

   random: get_random_u32 called from __get_random_u32_below+0x10/0x70 with crng_init=0

and in the process early boot messages had been lost (in addition to
making the messages that _hadn't_ been lost harder to read).

The proper way to find these things for the hypothetical developer that
cares - if such a person exists - is almost certainly with boot time
tracing.  That gives you the option to get call graphs etc too, which is
likely a requirement for fixing any problems anyway.

See Documentation/trace/boottime-trace.rst for that option.

And if we for some reason do want to re-introduce actual printing of
these things, it will need to have some uniqueness filtering rather than
this "just print it all" model.

Fixes: cc1e127bfa95 ("random: remove ratelimiting for in-kernel unseeded randomness")
Acked-by: Jason Donenfeld 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin