CVE-2024-57874 Information

Description

In the Linux kernel the following vulnerability has been resolved:

arm64: ptrace: fix partial SETREGSET for NT_ARM_TAGGED_ADDR_CTRL

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.

Reference

https://git.kernel.org/stable/c/1152dd13845efde5554f80c7e1233bae1d26bd3e https://git.kernel.org/stable/c/1370cf3eb5495d70e00547598583a4cd45b40b99 https://git.kernel.org/stable/c/1c176f5155ee6161fee6f416b64aa50394d3f220 https://git.kernel.org/stable/c/96035c0093db258975b8887676afe59a64c34a72 https://git.kernel.org/stable/c/abd614bbfcee73247495bd9472da8f85ac83546e https://git.kernel.org/stable/c/ca62d90085f4af36de745883faab9f8a7cbb45d3