user/sven/linux.git/include, branch v6.4.9

x86/srso: Add a Speculative RAS Overflow mitigation

2023-08-08T18:04:51Z

Upstream commit: fb3bd914b3ec28f5fb697ac55c4846ac2d542855 Add a mitigation for the speculative return address stack overflow vulnerability found on AMD processors. The mitigation works by ensuring all RET instructions speculate to a controlled location, similar to how speculation is controlled in the retpoline sequence. To accomplish this, the __x86_return_thunk forces the CPU to mispredict every function return using a 'safe return' sequence. To ensure the safety of this mitigation, the kernel must ensure that the safe return sequence is itself free from attacker interference. In Zen3 and Zen4, this is accomplished by creating a BTB alias between the untraining function srso_untrain_ret_alias() and the safe return function srso_safe_ret_alias() which results in evicting a potentially poisoned BTB entry and using that safe one for all function returns. In older Zen1 and Zen2, this is accomplished using a reinterpretation technique similar to Retbleed one: srso_untrain_ret() and srso_safe_ret(). Signed-off-by: Borislav Petkov (AMD) Signed-off-by: Greg Kroah-Hartman

init: Remove check_bugs() leftovers

2023-08-08T18:04:49Z

commit 61235b24b9cb37c13fcad5b9596d59a1afdcec30 upstream Everything is converted over to arch_cpu_finalize_init(). Remove the check_bugs() leftovers including the empty stubs in asm-generic, alpha, parisc, powerpc and xtensa. Signed-off-by: Thomas Gleixner Reviewed-by: Richard Henderson Link: https://lore.kernel.org/r/20230613224545.553215951@linutronix.de Signed-off-by: Daniel Sneddon Signed-off-by: Greg Kroah-Hartman

init: Provide arch_cpu_finalize_init()

2023-08-08T18:04:47Z

commit 7725acaa4f0c04fbefb0e0d342635b967bb7d414 upstream check_bugs() has become a dumping ground for all sorts of activities to finalize the CPU initialization before running the rest of the init code. Most are empty, a few do actual bug checks, some do alternative patching and some cobble a CPU advertisement string together.... Aside of that the current implementation requires duplicated function declaration and mostly empty header files for them. Provide a new function arch_cpu_finalize_init(). Provide a generic declaration if CONFIG_ARCH_HAS_CPU_FINALIZE_INIT is selected and a stub inline otherwise. This requires a temporary #ifdef in start_kernel() which will be removed along with check_bugs() once the architectures are converted over. Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20230613224544.957805717@linutronix.de Signed-off-by: Daniel Sneddon Signed-off-by: Greg Kroah-Hartman

dma-buf: keep the signaling time of merged fences v3

2023-08-03T08:26:14Z

commit f781f661e8c99b0cb34129f2e374234d61864e77 upstream. Some Android CTS is testing if the signaling time keeps consistent during merges. v2: use the current time if the fence is still in the signaling path and the timestamp not yet available. v3: improve comment, fix one more case to use the correct timestamp Signed-off-by: Christian König Reviewed-by: Luben Tuikov Link: https://patchwork.freedesktop.org/patch/msgid/20230630120041.109216-1-christian.koenig@amd.com Cc: Jindong Yue Signed-off-by: Greg Kroah-Hartman

mm: fix memory ordering for mm_lock_seq and vm_lock_seq

2023-08-03T08:26:14Z

commit b1f02b95758d05b799731d939e76a0bd6da312db upstream. mm->mm_lock_seq effectively functions as a read/write lock; therefore it must be used with acquire/release semantics. A specific example is the interaction between userfaultfd_register() and lock_vma_under_rcu(). userfaultfd_register() does the following from the point where it changes a VMA's flags to the point where concurrent readers are permitted again (in a simple scenario where only a single private VMA is accessed and no merging/splitting is involved): userfaultfd_register userfaultfd_set_vm_flags vm_flags_reset vma_start_write down_write(&vma->vm_lock->lock) vma->vm_lock_seq = mm_lock_seq [marks VMA as busy] up_write(&vma->vm_lock->lock) vm_flags_init [sets VM_UFFD_* in __vm_flags] vma->vm_userfaultfd_ctx.ctx = ctx mmap_write_unlock vma_end_write_all WRITE_ONCE(mm->mm_lock_seq, mm->mm_lock_seq + 1) [unlocks VMA] There are no memory barriers in between the __vm_flags update and the mm->mm_lock_seq update that unlocks the VMA, so the unlock can be reordered to above the `vm_flags_init()` call, which means from the perspective of a concurrent reader, a VMA can be marked as a userfaultfd VMA while it is not VMA-locked. That's bad, we definitely need a store-release for the unlock operation. The non-atomic write to vma->vm_lock_seq in vma_start_write() is mostly fine because all accesses to vma->vm_lock_seq that matter are always protected by the VMA lock. There is a racy read in vma_start_read() though that can tolerate false-positives, so we should be using WRITE_ONCE() to keep things tidy and data-race-free (including for KCSAN). On the other side, lock_vma_under_rcu() works as follows in the relevant region for locking and userfaultfd check: lock_vma_under_rcu vma_start_read vma->vm_lock_seq == READ_ONCE(vma->vm_mm->mm_lock_seq) [early bailout] down_read_trylock(&vma->vm_lock->lock) vma->vm_lock_seq == READ_ONCE(vma->vm_mm->mm_lock_seq) [main check] userfaultfd_armed checks vma->vm_flags & __VM_UFFD_FLAGS Here, the interesting aspect is how far down the mm->mm_lock_seq read can be reordered - if this read is reordered down below the vma->vm_flags access, this could cause lock_vma_under_rcu() to partly operate on information that was read while the VMA was supposed to be locked. To prevent this kind of downwards bleeding of the mm->mm_lock_seq read, we need to read it with a load-acquire. Some of the comment wording is based on suggestions by Suren. BACKPORT WARNING: One of the functions changed by this patch (which I've written against Linus' tree) is vma_try_start_write(), but this function no longer exists in mm/mm-everything. I don't know whether the merged version of this patch will be ordered before or after the patch that removes vma_try_start_write(). If you're backporting this patch to a tree with vma_try_start_write(), make sure this patch changes that function. Link: https://lkml.kernel.org/r/20230721225107.942336-1-jannh@google.com Fixes: 5e31275cc997 ("mm: add per-VMA lock and helper functions to control it") Signed-off-by: Jann Horn Reviewed-by: Suren Baghdasaryan Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

block: Fix a source code comment in include/uapi/linux/blkzoned.h

2023-08-03T08:25:57Z

[ Upstream commit e0933b526fbfd937c4a8f4e35fcdd49f0e22d411 ] Fix the symbolic names for zone conditions in the blkzoned.h header file. Cc: Hannes Reinecke Cc: Damien Le Moal Fixes: 6a0cb1bc106f ("block: Implement support for zoned block devices") Signed-off-by: Bart Van Assche Reviewed-by: Damien Le Moal Link: https://lore.kernel.org/r/20230706201422.3987341-1-bvanassche@acm.org Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

tcp: Reduce chance of collisions in inet6_hashfn().

2023-08-03T08:25:51Z

[ Upstream commit d11b0df7ddf1831f3e170972f43186dad520bfcc ] For both IPv4 and IPv6 incoming TCP connections are tracked in a hash table with a hash over the source & destination addresses and ports. However, the IPv6 hash is insufficient and can lead to a high rate of collisions. The IPv6 hash used an XOR to fit everything into the 96 bits for the fast jenkins hash, meaning it is possible for an external entity to ensure the hash collides, thus falling back to a linear search in the bucket, which is slow. We take the approach of hash the full length of IPv6 address in __ipv6_addr_jhash() so that all users can benefit from a more secure version. While this may look like it adds overhead, the reality of modern CPUs means that this is unmeasurable in real world scenarios. In simulating with llvm-mca, the increase in cycles for the hashing code was ~16 cycles on Skylake (from a base of ~155), and an extra ~9 on Nehalem (base of ~173). In commit dd6d2910c5e0 ("netfilter: conntrack: switch to siphash") netfilter switched from a jenkins hash to a siphash, but even the faster hsiphash is a more significant overhead (~20-30%) in some preliminary testing. So, in this patch, we keep to the more conservative approach to ensure we don't add much overhead per SYN. In testing, this results in a consistently even spread across the connection buckets. In both testing and real-world scenarios, we have not found any measurable performance impact. Fixes: 08dcdbf6a7b9 ("ipv6: use a stronger hash for tcp") Signed-off-by: Stewart Smith Signed-off-by: Samuel Mendoza-Jonas Suggested-by: Eric Dumazet Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20230721222410.17914-1-kuniyu@amazon.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

vxlan: calculate correct header length for GPE

2023-08-03T08:25:50Z

[ Upstream commit 94d166c5318c6edd1e079df8552233443e909c33 ] VXLAN-GPE does not add an extra inner Ethernet header. Take that into account when calculating header length. This causes problems in skb_tunnel_check_pmtu, where incorrect PMTU is cached. In the collect_md mode (which is the only mode that VXLAN-GPE supports), there's no magic auto-setting of the tunnel interface MTU. It can't be, since the destination and thus the underlying interface may be different for each packet. So, the administrator is responsible for setting the correct tunnel interface MTU. Apparently, the administrators are capable enough to calculate that the maximum MTU for VXLAN-GPE is (their_lower_MTU - 36). They set the tunnel interface MTU to 1464. If you run a TCP stream over such interface, it's then segmented according to the MTU 1464, i.e. producing 1514 bytes frames. Which is okay, this still fits the lower MTU. However, skb_tunnel_check_pmtu (called from vxlan_xmit_one) uses 50 as the header size and thus incorrectly calculates the frame size to be 1528. This leads to ICMP too big message being generated (locally), PMTU of 1450 to be cached and the TCP stream to be resegmented. The fix is to use the correct actual header size, especially for skb_tunnel_check_pmtu calculation. Fixes: e1e5314de08ba ("vxlan: implement GPE") Signed-off-by: Jiri Benc Reviewed-by: Simon Horman Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

tcp: annotate data-races around fastopenq.max_qlen

2023-07-27T06:57:05Z

[ Upstream commit 70f360dd7042cb843635ece9d28335a4addff9eb ] This field can be read locklessly. Fixes: 1536e2857bd3 ("tcp: Add a TCP_FASTOPEN socket option to get a max backlog on its listner") Signed-off-by: Eric Dumazet Link: https://lore.kernel.org/r/20230719212857.3943972-12-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

tcp: annotate data-races around tp->notsent_lowat

2023-07-27T06:57:05Z

[ Upstream commit 1aeb87bc1440c5447a7fa2d6e3c2cca52cbd206b ] tp->notsent_lowat can be read locklessly from do_tcp_getsockopt() and tcp_poll(). Fixes: c9bee3b7fdec ("tcp: TCP_NOTSENT_LOWAT socket option") Signed-off-by: Eric Dumazet Link: https://lore.kernel.org/r/20230719212857.3943972-10-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin