From: Mark Rutland mark.rutland@arm.com

stable inclusion from stable-v6.6.66 commit 96035c0093db258975b8887676afe59a64c34a72 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBIO47 CVE: CVE-2024-57874

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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Currently tagged_addr_ctrl_set() doesn't initialize the temporary 'ctrl' variable, and a SETREGSET call with a length of zero will leave this uninitialized. Consequently tagged_addr_ctrl_set() will consume an arbitrary value, potentially leaking up to 64 bits of memory from the kernel stack. The read is limited to a specific slot on the stack, and the issue does not provide a write mechanism.

As set_tagged_addr_ctrl() only accepts values where bits [63:4] zero and rejects other values, a partial SETREGSET attempt will randomly succeed or fail depending on the value of the uninitialized value, and the exposure is significantly limited.

Fix this by initializing the temporary value before copying the regset from userspace, as for other regsets (e.g. NT_PRSTATUS, NT_PRFPREG, NT_ARM_SYSTEM_CALL). In the case of a zero-length write, the existing value of the tagged address ctrl will be retained.

The NT_ARM_TAGGED_ADDR_CTRL regset is only visible in the user_aarch64_view used by a native AArch64 task to manipulate another native AArch64 task. As get_tagged_addr_ctrl() only returns an error value when called for a compat task, tagged_addr_ctrl_get() and tagged_addr_ctrl_set() should never observe an error value from get_tagged_addr_ctrl(). Add a WARN_ON_ONCE() to both to indicate that such an error would be unexpected, and error handlnig is not missing in either case.

Fixes: 2200aa7154cb ("arm64: mte: ptrace: Add NT_ARM_TAGGED_ADDR_CTRL regset") Cc: stable@vger.kernel.org # 5.10.x Signed-off-by: Mark Rutland mark.rutland@arm.com Cc: Will Deacon will@kernel.org Reviewed-by: Mark Brown broonie@kernel.org Link: https://lore.kernel.org/r/20241205121655.1824269-2-mark.rutland@arm.com Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Yuntao Liu liuyuntao12@huawei.com --- arch/arm64/kernel/ptrace.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 28a5ddcf0a1e..d34b57caad49 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -1384,7 +1384,7 @@ static int tagged_addr_ctrl_get(struct task_struct *target, { long ctrl = get_tagged_addr_ctrl(target);

- if (IS_ERR_VALUE(ctrl)) + if (WARN_ON_ONCE(IS_ERR_VALUE(ctrl))) return ctrl;

return membuf_write(&to, &ctrl, sizeof(ctrl)); @@ -1398,6 +1398,10 @@ static int tagged_addr_ctrl_set(struct task_struct *target, const struct int ret; long ctrl;

+ ctrl = get_tagged_addr_ctrl(target); + if (WARN_ON_ONCE(IS_ERR_VALUE(ctrl))) + return ctrl; + ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &ctrl, 0, -1); if (ret) return ret;