Mark DeviceFd::get_device_attr as unsafe #273
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argh, got ahead of myself, seems like CI found a missing unsafe block somewhere :(
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DeviceFd::get_device_attr should be marked as unsafe, because it allows writing to an arbitrary address. I have opened a kvm-ioctls PR[1] to fix this. The hypervisor crate was using the function unsafely by passing it addresses of immutable variables. I noticed this because an optimisation change[2] in Rust 1.80.0 caused the kvm::aarch64::gic::tests::test_get_set_icc_regs test to start failing when built in release mode. To fix this, I've broken up the _access functions into _set and _get variants, with the _get variant using a pointer to a mutable variable. This has the side effect of making these functions a bit nicer to use, because the caller now has no need to use references at all, for either getting or setting. [1]: rust-vmm/kvm#273 [2]: rust-lang/rust@d2d24e3 Signed-off-by: Alyssa Ross <[email protected]>
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DeviceFd::get_device_attr should be marked as unsafe, because it allows writing to an arbitrary address. I have opened a kvm-ioctls PR[1] to fix this. The hypervisor crate was using the function unsafely by passing it addresses of immutable variables. I noticed this because an optimisation change[2] in Rust 1.80.0 caused the kvm::aarch64::gic::tests::test_get_set_icc_regs test to start failing when built in release mode. To fix this, I've broken up the _access functions into _set and _get variants, with the _get variant using a pointer to a mutable variable. This has the side effect of making these functions a bit nicer to use, because the caller now has no need to use references at all, for either getting or setting. [1]: rust-vmm/kvm#273 [2]: rust-lang/rust@d2d24e3 Signed-off-by: Alyssa Ross <[email protected]>
KVM_GET_DEVICE_ATTR causes the kernel to write to an arbitrary address. This is unsafe, as it can allow writing to an address Rust believes to be immutable. I discovered this because an optimisation change[1] in Rust 1.80.0 caused a Cloud Hypervisor test to start failing when built in release mode, because it was setting the addr passed to get_device_attr() to the address of an immutable variable. [1]: rust-lang/rust@d2d24e3 Fixes: 8ea124b ("Add support for `KVM_GET_DEVICE_ATTR` ioctl") Signed-off-by: Alyssa Ross <[email protected]>
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DeviceFd::get_device_attr should be marked as unsafe, because it allows writing to an arbitrary address. I have opened a kvm-ioctls PR[1] to fix this. The hypervisor crate was using the function unsafely by passing it addresses of immutable variables. I noticed this because an optimisation change[2] in Rust 1.80.0 caused the kvm::aarch64::gic::tests::test_get_set_icc_regs test to start failing when built in release mode. To fix this, I've broken up the _access functions into _set and _get variants, with the _get variant using a pointer to a mutable variable. This has the side effect of making these functions a bit nicer to use, because the caller now has no need to use references at all, for either getting or setting. [1]: rust-vmm/kvm#273 [2]: rust-lang/rust@d2d24e3 Signed-off-by: Alyssa Ross <[email protected]>
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DeviceFd::get_device_attr should be marked as unsafe, because it allows writing to an arbitrary address. I have opened a kvm-ioctls PR[1] to fix this. The hypervisor crate was using the function unsafely by passing it addresses of immutable variables. I noticed this because an optimisation change[2] in Rust 1.80.0 caused the kvm::aarch64::gic::tests::test_get_set_icc_regs test to start failing when built in release mode. To fix this, I've broken up the _access functions into _set and _get variants, with the _get variant using a pointer to a mutable variable. This has the side effect of making these functions a bit nicer to use, because the caller now has no need to use references at all, for either getting or setting. [1]: rust-vmm/kvm#273 [2]: rust-lang/rust@d2d24e3 Signed-off-by: Alyssa Ross <[email protected]>
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DeviceFd::get_device_attr should be marked as unsafe, because it allows writing to an arbitrary address. I have opened a kvm-ioctls PR[1] to fix this. The hypervisor crate was using the function unsafely by passing it addresses of immutable variables. I noticed this because an optimisation change[2] in Rust 1.80.0 caused the kvm::aarch64::gic::tests::test_get_set_icc_regs test to start failing when built in release mode. To fix this, I've broken up the _access functions into _set and _get variants, with the _get variant using a pointer to a mutable variable. This has the side effect of making these functions a bit nicer to use, because the caller now has no need to use references at all, for either getting or setting. [1]: rust-vmm/kvm#273 [2]: rust-lang/rust@d2d24e3 Signed-off-by: Alyssa Ross <[email protected]>
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DeviceFd::get_device_attr should be marked as unsafe, because it allows writing to an arbitrary address. I have opened a kvm-ioctls PR[1] to fix this. The hypervisor crate was using the function unsafely by passing it addresses of immutable variables. I noticed this because an optimisation change[2] in Rust 1.80.0 caused the kvm::aarch64::gic::tests::test_get_set_icc_regs test to start failing when built in release mode. To fix this, I've broken up the _access functions into _set and _get variants, with the _get variant using a pointer to a mutable variable. This has the side effect of making these functions a bit nicer to use, because the caller now has no need to use references at all, for either getting or setting. [1]: rust-vmm/kvm#273 [2]: rust-lang/rust@d2d24e3 Signed-off-by: Alyssa Ross <[email protected]>
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DeviceFd::get_device_attr should be marked as unsafe, because it allows writing to an arbitrary address. I have opened a kvm-ioctls PR[1] to fix this. The hypervisor crate was using the function unsafely by passing it addresses of immutable variables. I noticed this because an optimisation change[2] in Rust 1.80.0 caused the kvm::aarch64::gic::tests::test_get_set_icc_regs test to start failing when built in release mode. To fix this, I've broken up the _access functions into _set and _get variants, with the _get variant using a pointer to a mutable variable. This has the side effect of making these functions a bit nicer to use, because the caller now has no need to use references at all, for either getting or setting. [1]: rust-vmm/kvm#273 [2]: rust-lang/rust@d2d24e3 Signed-off-by: Alyssa Ross <[email protected]>
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DeviceFd::get_device_attr should be marked as unsafe, because it allows writing to an arbitrary address. I have opened a kvm-ioctls PR[1] to fix this. The hypervisor crate was using the function unsafely by passing it addresses of immutable variables. I noticed this because an optimisation change[2] in Rust 1.80.0 caused the kvm::aarch64::gic::tests::test_get_set_icc_regs test to start failing when built in release mode. To fix this, I've broken up the _access functions into _set and _get variants, with the _get variant using a pointer to a mutable variable. This has the side effect of making these functions a bit nicer to use, because the caller now has no need to use references at all, for either getting or setting. [1]: rust-vmm/kvm#273 [2]: rust-lang/rust@d2d24e3 Signed-off-by: Alyssa Ross <[email protected]> (cherry picked from commit 02f146f)
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Summary of the PR
KVM_GET_DEVICE_ATTRcauses the kernel to write to an arbitrary address. This is unsafe, as it can allow writing to an address Rust believes to be immutable.I discovered this because an optimisation change in Rust 1.80.0 caused a Cloud Hypervisor test to start failing when built in release mode, because it was setting the addr passed to
get_device_attr()to the address of an immutable variable.Requirements
Before submitting your PR, please make sure you addressed the following
requirements:
git commit -s), and the commit message has max 60 characters for thesummary and max 75 characters for each description line.
test.
Release" section of CHANGELOG.md (if no such section exists, please create one).
unsafecode is properly documented.