| Filename | Latest commit message | Latest commit date |
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commit b3583fca5fb654af2cfc1c08259abb9728272538 upstream.
If both the tracer and the tracee are compat processes, and gprs[2]
is assigned a value by __poke_user_compat, then the higher 32 bits
of gprs[2] are cleared, IS_ERR_VALUE() always returns false, and
syscall_get_error() always returns 0.
Fix the implementation by sign-extending the value for compat processes
the same way as x86 implementation does.
The bug was exposed to user space by commit 201766a20e30f ("ptrace: add
PTRACE_GET_SYSCALL_INFO request") and detected by strace test suite.
This change fixes strace syscall tampering on s390.
Link: https://lkml.kernel.org/r/20200602180051.GA2427@altlinux.org
Fixes:
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| .. | ||
| asm | ||
| uapi/asm | ||