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2c1dde8a69
Shivaprasad reported a boot failure due to userspace processes crash on
abort() from libc.so.6. It was bisected to merge request
commit '3424d8c18a7d ("Merge tag 'core-entry-2026-08-17' of
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip")'
Upon checking the merge, when syscall_enter_from_user_mode_randomize_stack
fails, which could happen when a tracer like seccomp or ptrace intercepts
and skips the syscall, the code returns to userspace immediately without
clearing the intermediate flag which was set.
When the next syscall is made, it immediately aborts the valid syscall
since the flag is still set. Hence clear the flag on occurrence of first
failure.
Reported-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
Closes: https://lore.kernel.org/all/e301014d-568f-4ed5-bc64-b8a85ca0b1e1@linux.ibm.com/
Fixes: 3424d8c18a ("Merge tag 'core-entry-2026-08-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip")
Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Tested-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
Reviewed-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260828053811.1042300-1-sshegde@linux.ibm.com
69 lines
1.7 KiB
C
69 lines
1.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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#include <linux/compat.h>
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#include <linux/context_tracking.h>
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#include <linux/entry-common.h>
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#include <asm/interrupt.h>
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#include <asm/kup.h>
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#include <asm/syscall.h>
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#include <asm/time.h>
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#include <asm/tm.h>
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#include <asm/unistd.h>
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/* Has to run notrace because it is entered not completely "reconciled" */
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notrace long system_call_exception(struct pt_regs *regs, unsigned long r0)
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{
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long ret;
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syscall_fn f;
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if (unlikely(!syscall_enter_from_user_mode_randomize_stack(regs, &r0))) {
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clear_thread_flag(TIF_SYSCALL_RET);
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return syscall_get_error(current, regs);
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}
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if (unlikely(test_and_clear_thread_flag(TIF_SYSCALL_RET)))
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return syscall_get_error(current, regs);
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if (unlikely(r0 >= NR_syscalls)) {
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if (unlikely(trap_is_unsupported_scv(regs))) {
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/* Unsupported scv vector */
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_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
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return regs->gpr[3];
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}
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return -ENOSYS;
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}
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/* May be faster to do array_index_nospec? */
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barrier_nospec();
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#ifdef CONFIG_ARCH_HAS_SYSCALL_WRAPPER
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// No COMPAT if we have SYSCALL_WRAPPER, see Kconfig
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f = (void *)sys_call_table[r0];
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ret = f(regs);
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#else
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if (unlikely(is_compat_task())) {
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unsigned long r3, r4, r5, r6, r7, r8;
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f = (void *)compat_sys_call_table[r0];
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r3 = regs->gpr[3] & 0x00000000ffffffffULL;
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r4 = regs->gpr[4] & 0x00000000ffffffffULL;
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r5 = regs->gpr[5] & 0x00000000ffffffffULL;
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r6 = regs->gpr[6] & 0x00000000ffffffffULL;
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r7 = regs->gpr[7] & 0x00000000ffffffffULL;
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r8 = regs->gpr[8] & 0x00000000ffffffffULL;
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ret = f(r3, r4, r5, r6, r7, r8);
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} else {
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f = (void *)sys_call_table[r0];
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ret = f(regs->gpr[3], regs->gpr[4], regs->gpr[5],
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regs->gpr[6], regs->gpr[7], regs->gpr[8]);
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}
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#endif
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return ret;
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}
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