capabilities: fix undefined behavior in bit shift for CAP_TO_MASK

Shifting signed 32-bit value by 31 bits is undefined, so changing significant bit to unsigned. The UBSAN warning calltrace like below: UBSAN: shift-out-of-bounds in security/commoncap.c:1252:2 left shift of 1 by 31 places cannot be represented in type 'int' Call Trace: <TASK> dump_stack_lvl+0x7d/0xa5 dump_stack+0x15/0x1b ubsan_epilogue+0xe/0x4e __ubsan_handle_shift_out_of_bounds+0x1e7/0x20c cap_task_prctl+0x561/0x6f0 security_task_prctl+0x5a/0xb0 __x64_sys_prctl+0x61/0x8f0 do_syscall_64+0x58/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd </TASK>

Gaosheng Cui committed 4 years ago

Commit 46653971 parent 8cf0a1b1 file · +1 −1Browse files

Showing the changes to include/uapi/linux (1 of 1 file). Show all

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include/uapi/linux/capability.h+1−1

@@ -426,7 +426,7 @@ struct vfs_ns_cap_data { · 425 unmodified lines
426	426	*/
427	427
428	428	#define CAP_TO_INDEX(x) ((x) >> 5) /* 1 << 5 == bits in __u32 */
429		−#define CAP_TO_MASK(x) (1 << ((x) & 31)) /* mask for indexed __u32 */
	429	+#define CAP_TO_MASK(x) (1U << ((x) & 31)) /* mask for indexed __u32 */
430	430
431	431
432	432	#endif /* _UAPI_LINUX_CAPABILITY_H */