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| author |   Heiko Carstens <heiko.carstens@de.ibm.com> | 2017-02-17 08:13:28 +0100 |
|---|---|---|
| committer |   Martin Schwidefsky <schwidefsky@de.ibm.com> | 2017-02-23 10:06:38 +0100 |
| commit | b5a882fcf146c87cb6b67c6df353e1c042b8773d (patch) | |
| tree | a5c7d041f74567d24d44c17a1f80e86302d738d5 /arch/s390/include/asm/processor.h | |
| parent | s390: rename CIF_ASCE to CIF_ASCE_PRIMARY (diff) | |
| download | linux-dev-b5a882fcf146c87cb6b67c6df353e1c042b8773d.tar.xz linux-dev-b5a882fcf146c87cb6b67c6df353e1c042b8773d.zip | |
s390: restore address space when returning to user space
Unbalanced set_fs usages (e.g. early exit from a function and a
forgotten set_fs(USER_DS) call) may lead to a situation where the
secondary asce is the kernel space asce when returning to user
space. This would allow user space to modify kernel space at will.
This would only be possible with the above mentioned kernel bug,
however we can detect this and fix the secondary asce before returning
to user space.
Therefore a new TIF_ASCE_SECONDARY which is used within set_fs. When
returning to user space check if TIF_ASCE_SECONDARY is set, which
would indicate a bug. If it is set print a message to the console,
fixup the secondary asce, and then return to user space.
This is similar to what is being discussed for x86 and arm:
"[RFC] syscalls: Restore address limit after a syscall".
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/processor.h')
| -rw-r--r-- | arch/s390/include/asm/processor.h | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h index 3c8fae02ac2d..c57c5c2f2484 100644 --- a/arch/s390/include/asm/processor.h +++ b/arch/s390/include/asm/processor.h @@ -15,13 +15,15 @@ #define CIF_MCCK_PENDING 0 /* machine check handling is pending */ #define CIF_ASCE_PRIMARY 1 /* primary asce needs fixup / uaccess */ -#define CIF_NOHZ_DELAY 2 /* delay HZ disable for a tick */ -#define CIF_FPU 3 /* restore FPU registers */ -#define CIF_IGNORE_IRQ 4 /* ignore interrupt (for udelay) */ -#define CIF_ENABLED_WAIT 5 /* in enabled wait state */ +#define CIF_ASCE_SECONDARY 2 /* secondary asce needs fixup / uaccess */ +#define CIF_NOHZ_DELAY 3 /* delay HZ disable for a tick */ +#define CIF_FPU 4 /* restore FPU registers */ +#define CIF_IGNORE_IRQ 5 /* ignore interrupt (for udelay) */ +#define CIF_ENABLED_WAIT 6 /* in enabled wait state */ #define _CIF_MCCK_PENDING _BITUL(CIF_MCCK_PENDING) #define _CIF_ASCE_PRIMARY _BITUL(CIF_ASCE_PRIMARY) +#define _CIF_ASCE_SECONDARY _BITUL(CIF_ASCE_SECONDARY) #define _CIF_NOHZ_DELAY _BITUL(CIF_NOHZ_DELAY) #define _CIF_FPU _BITUL(CIF_FPU) #define _CIF_IGNORE_IRQ _BITUL(CIF_IGNORE_IRQ) @@ -200,10 +202,12 @@ struct stack_frame { struct task_struct; struct mm_struct; struct seq_file; +struct pt_regs; typedef int (*dump_trace_func_t)(void *data, unsigned long address, int reliable); void dump_trace(dump_trace_func_t func, void *data, struct task_struct *task, unsigned long sp); +void show_registers(struct pt_regs *regs); void show_cacheinfo(struct seq_file *m); |