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dump/ppc64,arm,mips: sanitize the ERESTART_RESTARTBLOCK -> EINTR transition

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1. The -ERESTART_RESTARTBLOCK case in get_task_regs() depends on kernel
   internals too much, and for no reason. We shouldn't rely on fact that
   a) we are going to do sigreturn() and b) restore_sigcontext() always
   sets restart_block->fn = do_no_restart_syscall which returns -EINTR.

   Just change this code to enforce -EINTR after restore, this is what
   we actually want until we teach criu to handle ERESTART_RESTARTBLOCK.

2. Add pr_warn() to make the potential bug-reports more understandable,
   a sane application should handle -EINTR correctly but this is not
   always the case.

Fixes: #1325
Report-by: Mr Travis
Inspired-by: dd71cca58ada ("dump/x86: sanitize the ERESTART_RESTARTBLOCK -> EINTR transition")
Signed-off-by: Andrei Vagin <avagin@gmail.com>
This commit is contained in:
Andrei Vagin 2021-01-01 01:21:44 +03:00
parent 0cbfba7780
commit c7544894fe
3 changed files with 10 additions and 7 deletions
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6
compel/arch/arm/src/lib/infect.c
View File

@ -4,6 +4,8 @@
#include <string.h>
#include <compel/plugins/std/syscall-codes.h>
#include <compel/asm/processor-flags.h>
#include <errno.h>
#include "common/page.h"
#include "uapi/compel/asm/infect-types.h"
#include "log.h"
@ -91,8 +93,8 @@ int get_task_regs(pid_t pid, user_regs_struct_t *regs, save_regs_t save,
regs->ARM_pc -= 4;
break;
case -ERESTART_RESTARTBLOCK:
regs->ARM_r0 = __NR_restart_syscall;
regs->ARM_pc -= 4;
pr_warn("Will restore %d with interrupted system call\n", pid);
regs->ARM_r0 = -EINTR;
break;
}
}

7
compel/arch/mips/src/lib/infect.c
View File

@ -2,6 +2,8 @@
#include <sys/uio.h>
#include <sys/auxv.h>
#include <sys/mman.h>
#include <errno.h>
#include <compel/asm/fpu.h>
#include <compel/cpu.h>
#include "errno.h"
@ -142,9 +144,8 @@ int get_task_regs(pid_t pid, user_regs_struct_t *regs, save_regs_t save,
regs->cp0_epc -= 4;
break;
case ERESTART_RESTARTBLOCK:
regs->regs[2] = __NR_restart_syscall;
regs->regs[7] = regs->regs[26];
regs->cp0_epc -= 4;
pr_warn("Will restore %d with interrupted system call\n", pid);
regs->regs[2] = -EINTR;
break;
}
regs->regs[0] = 0;

4
compel/arch/ppc64/src/lib/infect.c
View File

@ -330,8 +330,8 @@ static int __get_task_regs(pid_t pid, user_regs_struct_t *regs,
regs->nip -= 4;
break;
case ERESTART_RESTARTBLOCK:
regs->gpr[0] = __NR_restart_syscall;
regs->nip -= 4;
pr_warn("Will restore %d with interrupted system call\n", pid);
regs->gpr[3] = EINTR;
break;
}
}