Bug 2502544 (CVE-2026-64082)

Summary: CVE-2026-64082 kernel: riscv: Fix register corruption from uninitialized cregs on error
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel, specifically within the RISC-V architecture's handling of process tracing and signal restoration. When functions like `compat_riscv_gpr_set()` or `compat_restore_sigcontext()` are invoked, they may process uninitialized stack data if a preceding user data copy operation fails. This can lead to the corruption of a task's register state and potentially leak sensitive kernel stack contents, resulting in information disclosure and a denial of service.
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Description OSIDB Bzimport 2026-07-19 17:05:18 UTC 
In the Linux kernel, the following vulnerability has been resolved:

riscv: Fix register corruption from uninitialized cregs on error

compat_riscv_gpr_set() calls cregs_to_regs() unconditionally, even when
user_regset_copyin() fails. Since cregs is an uninitialized stack
variable, a copyin failure causes uninitialized stack data to be written
into the target task's pt_regs, corrupting its register state and
potentially leaking kernel stack contents.

compat_restore_sigcontext() has the same issue: it calls cregs_to_regs()
even when __copy_from_user() fails, leading to the same corruption of
the signal-returning task's register state on error.

Only call cregs_to_regs() when the user copy succeeds.
Comment 1 TEJ RATHI 2026-07-20 14:21:52 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026071915-CVE-2026-64082-bf76@gregkh/T