kernel/linux.git, branch v5.4.210

Linux 5.4.210

2022-08-11T10:57:53+00:00

Link: https://lore.kernel.org/r/20220809175510.312431319@linuxfoundation.org Tested-by: Florian Fainelli Tested-by: Linux Kernel Functional Testing Tested-by: Sudip Mukherjee Tested-by: Guenter Roeck Tested-by: Jon Hunter Tested-by: Shuah Khan Signed-off-by: Greg Kroah-Hartman

x86/speculation: Add LFENCE to RSB fill sequence

2022-08-11T10:57:53+00:00

commit ba6e31af2be96c4d0536f2152ed6f7b6c11bca47 upstream. RSB fill sequence does not have any protection for miss-prediction of conditional branch at the end of the sequence. CPU can speculatively execute code immediately after the sequence, while RSB filling hasn't completed yet. #define __FILL_RETURN_BUFFER(reg, nr, sp) \ mov $(nr/2), reg; \ 771: \ call 772f; \ 773: /* speculation trap */ \ pause; \ lfence; \ jmp 773b; \ 772: \ call 774f; \ 775: /* speculation trap */ \ pause; \ lfence; \ jmp 775b; \ 774: \ dec reg; \ jnz 771b; <----- CPU can miss-predict here. \ add $(BITS_PER_LONG/8) * nr, sp; Before RSB is filled, RETs that come in program order after this macro can be executed speculatively, making them vulnerable to RSB-based attacks. Mitigate it by adding an LFENCE after the conditional branch to prevent speculation while RSB is being filled. Suggested-by: Andrew Cooper Signed-off-by: Pawan Gupta Signed-off-by: Borislav Petkov Signed-off-by: Greg Kroah-Hartman

x86/speculation: Add RSB VM Exit protections

2022-08-11T10:57:53+00:00

commit 2b1299322016731d56807aa49254a5ea3080b6b3 upstream. tl;dr: The Enhanced IBRS mitigation for Spectre v2 does not work as documented for RET instructions after VM exits. Mitigate it with a new one-entry RSB stuffing mechanism and a new LFENCE. == Background == Indirect Branch Restricted Speculation (IBRS) was designed to help mitigate Branch Target Injection and Speculative Store Bypass, i.e. Spectre, attacks. IBRS prevents software run in less privileged modes from affecting branch prediction in more privileged modes. IBRS requires the MSR to be written on every privilege level change. To overcome some of the performance issues of IBRS, Enhanced IBRS was introduced. eIBRS is an "always on" IBRS, in other words, just turn it on once instead of writing the MSR on every privilege level change. When eIBRS is enabled, more privileged modes should be protected from less privileged modes, including protecting VMMs from guests. == Problem == Here's a simplification of how guests are run on Linux' KVM: void run_kvm_guest(void) { // Prepare to run guest VMRESUME(); // Clean up after guest runs } The execution flow for that would look something like this to the processor: 1. Host-side: call run_kvm_guest() 2. Host-side: VMRESUME 3. Guest runs, does "CALL guest_function" 4. VM exit, host runs again 5. Host might make some "cleanup" function calls 6. Host-side: RET from run_kvm_guest() Now, when back on the host, there are a couple of possible scenarios of post-guest activity the host needs to do before executing host code: * on pre-eIBRS hardware (legacy IBRS, or nothing at all), the RSB is not touched and Linux has to do a 32-entry stuffing. * on eIBRS hardware, VM exit with IBRS enabled, or restoring the host IBRS=1 shortly after VM exit, has a documented side effect of flushing the RSB except in this PBRSB situation where the software needs to stuff the last RSB entry "by hand". IOW, with eIBRS supported, host RET instructions should no longer be influenced by guest behavior after the host retires a single CALL instruction. However, if the RET instructions are "unbalanced" with CALLs after a VM exit as is the RET in #6, it might speculatively use the address for the instruction after the CALL in #3 as an RSB prediction. This is a problem since the (untrusted) guest controls this address. Balanced CALL/RET instruction pairs such as in step #5 are not affected. == Solution == The PBRSB issue affects a wide variety of Intel processors which support eIBRS. But not all of them need mitigation. Today, X86_FEATURE_RETPOLINE triggers an RSB filling sequence that mitigates PBRSB. Systems setting RETPOLINE need no further mitigation - i.e., eIBRS systems which enable retpoline explicitly. However, such systems (X86_FEATURE_IBRS_ENHANCED) do not set RETPOLINE and most of them need a new mitigation. Therefore, introduce a new feature flag X86_FEATURE_RSB_VMEXIT_LITE which triggers a lighter-weight PBRSB mitigation versus RSB Filling at vmexit. The lighter-weight mitigation performs a CALL instruction which is immediately followed by a speculative execution barrier (INT3). This steers speculative execution to the barrier -- just like a retpoline -- which ensures that speculation can never reach an unbalanced RET. Then, ensure this CALL is retired before continuing execution with an LFENCE. In other words, the window of exposure is opened at VM exit where RET behavior is troublesome. While the window is open, force RSB predictions sampling for RET targets to a dead end at the INT3. Close the window with the LFENCE. There is a subset of eIBRS systems which are not vulnerable to PBRSB. Add these systems to the cpu_vuln_whitelist[] as NO_EIBRS_PBRSB. Future systems that aren't vulnerable will set ARCH_CAP_PBRSB_NO. [ bp: Massage, incorporate review comments from Andy Cooper. ] [ Pawan: Update commit message to replace RSB_VMEXIT with RETPOLINE ] Signed-off-by: Daniel Sneddon Co-developed-by: Pawan Gupta Signed-off-by: Pawan Gupta Signed-off-by: Borislav Petkov Signed-off-by: Greg Kroah-Hartman

macintosh/adb: fix oob read in do_adb_query() function

2022-08-11T10:57:53+00:00

commit fd97e4ad6d3b0c9fce3bca8ea8e6969d9ce7423b upstream. In do_adb_query() function of drivers/macintosh/adb.c, req->data is copied form userland. The parameter "req->data[2]" is missing check, the array size of adb_handler[] is 16, so adb_handler[req->data[2]].original_address and adb_handler[req->data[2]].handler_id will lead to oob read. Cc: stable Signed-off-by: Ning Qiang Reviewed-by: Kees Cook Reviewed-by: Greg Kroah-Hartman Acked-by: Benjamin Herrenschmidt Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220713153734.2248-1-sohu0106@126.com Signed-off-by: Greg Kroah-Hartman

media: v4l2-mem2mem: Apply DST_QUEUE_OFF_BASE on MMAP buffers across ioctls

2022-08-11T10:57:52+00:00

commit 8310ca94075e784bbb06593cd6c068ee6b6e4ca6 upstream. DST_QUEUE_OFF_BASE is applied to offset/mem_offset on MMAP capture buffers only for the VIDIOC_QUERYBUF ioctl, while the userspace fields (including offset/mem_offset) are filled in for VIDIOC_{QUERY,PREPARE,Q,DQ}BUF ioctls. This leads to differences in the values presented to userspace. If userspace attempts to mmap the capture buffer directly using values from DQBUF, it will fail. Move the code that applies the magic offset into a helper, and call that helper from all four ioctl entry points. [hverkuil: drop unnecessary '= 0' in v4l2_m2m_querybuf() for ret] Fixes: 7f98639def42 ("V4L/DVB: add memory-to-memory device helper framework for videobuf") Fixes: 908a0d7c588e ("[media] v4l: mem2mem: port to videobuf2") Signed-off-by: Chen-Yu Tsai Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab [OP: backport to 5.4: adjusted return logic in v4l2_m2m_qbuf() to match the logic in the original commit: call v4l2_m2m_adjust_mem_offset() only if !ret and before the v4l2_m2m_try_schedule() call] Signed-off-by: Ovidiu Panait Signed-off-by: Greg Kroah-Hartman

selftests: KVM: Handle compiler optimizations in ucall

2022-08-11T10:57:52+00:00

[ Upstream commit 9e2f6498efbbc880d7caa7935839e682b64fe5a6 ] The selftests, when built with newer versions of clang, is found to have over optimized guests' ucall() function, and eliminating the stores for uc.cmd (perhaps due to no immediate readers). This resulted in the userspace side always reading a value of '0', and causing multiple test failures. As a result, prevent the compiler from optimizing the stores in ucall() with WRITE_ONCE(). Suggested-by: Ricardo Koller Suggested-by: Reiji Watanabe Signed-off-by: Raghavendra Rao Ananta Message-Id: <20220615185706.1099208-1-rananta@google.com> Reviewed-by: Andrew Jones Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin

KVM: Don't null dereference ops->destroy

2022-08-11T10:57:52+00:00

[ Upstream commit e8bc2427018826e02add7b0ed0fc625a60390ae5 ] A KVM device cleanup happens in either of two callbacks: 1) destroy() which is called when the VM is being destroyed; 2) release() which is called when a device fd is closed. Most KVM devices use 1) but Book3s's interrupt controller KVM devices (XICS, XIVE, XIVE-native) use 2) as they need to close and reopen during the machine execution. The error handling in kvm_ioctl_create_device() assumes destroy() is always defined which leads to NULL dereference as discovered by Syzkaller. This adds a checks for destroy!=NULL and adds a missing release(). This is not changing kvm_destroy_devices() as devices with defined release() should have been removed from the KVM devices list by then. Suggested-by: Paolo Bonzini Signed-off-by: Alexey Kardashevskiy Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin

selftests/bpf: Fix "dubious pointer arithmetic" test

2022-08-11T10:57:52+00:00

commit 3615bdf6d9b19db12b1589861609b4f1c6a8d303 upstream. The verifier trace changed following a bugfix. After checking the 64-bit sign, only the upper bit mask is known, not bit 31. Update the test accordingly. Signed-off-by: Jean-Philippe Brucker Acked-by: John Fastabend Signed-off-by: Alexei Starovoitov Signed-off-by: Ovidiu Panait Signed-off-by: Greg Kroah-Hartman

selftests/bpf: Fix test_align verifier log patterns

2022-08-11T10:57:52+00:00

commit 5366d2269139ba8eb6a906d73a0819947e3e4e0a upstream. Commit 294f2fc6da27 ("bpf: Verifer, adjust_scalar_min_max_vals to always call update_reg_bounds()") changed the way verifier logs some of its state, adjust the test_align accordingly. Where possible, I tried to not copy-paste the entire log line and resorted to dropping the last closing brace instead. Fixes: 294f2fc6da27 ("bpf: Verifer, adjust_scalar_min_max_vals to always call update_reg_bounds()") Signed-off-by: Stanislav Fomichev Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20200515194904.229296-1-sdf@google.com Signed-off-by: Ovidiu Panait Signed-off-by: Greg Kroah-Hartman

bpf: Test_verifier, #70 error message updates for 32-bit right shift

2022-08-11T10:57:51+00:00

commit aa131ed44ae1d76637f0dbec33cfcf9115af9bc3 upstream. After changes to add update_reg_bounds after ALU ops and adding ALU32 bounds tracking the error message is changed in the 32-bit right shift tests. Test "#70/u bounds check after 32-bit right shift with 64-bit input FAIL" now fails with, Unexpected error message! EXP: R0 invalid mem access RES: func#0 @0 7: (b7) r1 = 2 8: R0_w=map_value(id=0,off=0,ks=8,vs=8,imm=0) R1_w=invP2 R10=fp0 fp-8_w=mmmmmmmm 8: (67) r1 <<= 31 9: R0_w=map_value(id=0,off=0,ks=8,vs=8,imm=0) R1_w=invP4294967296 R10=fp0 fp-8_w=mmmmmmmm 9: (74) w1 >>= 31 10: R0_w=map_value(id=0,off=0,ks=8,vs=8,imm=0) R1_w=invP0 R10=fp0 fp-8_w=mmmmmmmm 10: (14) w1 -= 2 11: R0_w=map_value(id=0,off=0,ks=8,vs=8,imm=0) R1_w=invP4294967294 R10=fp0 fp-8_w=mmmmmmmm 11: (0f) r0 += r1 math between map_value pointer and 4294967294 is not allowed And test "#70/p bounds check after 32-bit right shift with 64-bit input FAIL" now fails with, Unexpected error message! EXP: R0 invalid mem access RES: func#0 @0 7: (b7) r1 = 2 8: R0_w=map_value(id=0,off=0,ks=8,vs=8,imm=0) R1_w=inv2 R10=fp0 fp-8_w=mmmmmmmm 8: (67) r1 <<= 31 9: R0_w=map_value(id=0,off=0,ks=8,vs=8,imm=0) R1_w=inv4294967296 R10=fp0 fp-8_w=mmmmmmmm 9: (74) w1 >>= 31 10: R0_w=map_value(id=0,off=0,ks=8,vs=8,imm=0) R1_w=inv0 R10=fp0 fp-8_w=mmmmmmmm 10: (14) w1 -= 2 11: R0_w=map_value(id=0,off=0,ks=8,vs=8,imm=0) R1_w=inv4294967294 R10=fp0 fp-8_w=mmmmmmmm 11: (0f) r0 += r1 last_idx 11 first_idx 0 regs=2 stack=0 before 10: (14) w1 -= 2 regs=2 stack=0 before 9: (74) w1 >>= 31 regs=2 stack=0 before 8: (67) r1 <<= 31 regs=2 stack=0 before 7: (b7) r1 = 2 math between map_value pointer and 4294967294 is not allowed Before this series we did not trip the "math between map_value pointer..." error because check_reg_sane_offset is never called in adjust_ptr_min_max_vals(). Instead we have a register state that looks like this at line 11*, 11: R0_w=map_value(id=0,off=0,ks=8,vs=8, smin_value=0,smax_value=0, umin_value=0,umax_value=0, var_off=(0x0; 0x0)) R1_w=invP(id=0, smin_value=0,smax_value=4294967295, umin_value=0,umax_value=4294967295, var_off=(0xfffffffe; 0x0)) R10=fp(id=0,off=0, smin_value=0,smax_value=0, umin_value=0,umax_value=0, var_off=(0x0; 0x0)) fp-8_w=mmmmmmmm 11: (0f) r0 += r1 In R1 'smin_val != smax_val' yet we have a tnum_const as seen by 'var_off(0xfffffffe; 0x0))' with a 0x0 mask. So we hit this check in adjust_ptr_min_max_vals() if ((known && (smin_val != smax_val || umin_val != umax_val)) || smin_val > smax_val || umin_val > umax_val) { /* Taint dst register if offset had invalid bounds derived from * e.g. dead branches. */ __mark_reg_unknown(env, dst_reg); return 0; } So we don't throw an error here and instead only throw an error later in the verification when the memory access is made. The root cause in verifier without alu32 bounds tracking is having 'umin_value = 0' and 'umax_value = U64_MAX' from BPF_SUB which we set when 'umin_value < umax_val' here, if (dst_reg->umin_value < umax_val) { /* Overflow possible, we know nothing */ dst_reg->umin_value = 0; dst_reg->umax_value = U64_MAX; } else { ...} Later in adjust_calar_min_max_vals we previously did a coerce_reg_to_size() which will clamp the U64_MAX to U32_MAX by truncating to 32bits. But either way without a call to update_reg_bounds the less precise bounds tracking will fall out of the alu op verification. After latest changes we now exit adjust_scalar_min_max_vals with the more precise umin value, due to zero extension propogating bounds from alu32 bounds into alu64 bounds and then calling update_reg_bounds. This then causes the verifier to trigger an earlier error and we get the error in the output above. This patch updates tests to reflect new error message. * I have a local patch to print entire verifier state regardless if we believe it is a constant so we can get a full picture of the state. Usually if tnum_is_const() then bounds are also smin=smax, etc. but this is not always true and is a bit subtle. Being able to see these states helps understand dataflow imo. Let me know if we want something similar upstream. Signed-off-by: John Fastabend Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/158507161475.15666.3061518385241144063.stgit@john-Precision-5820-Tower Signed-off-by: Ovidiu Panait Signed-off-by: Greg Kroah-Hartman