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capabilities: fix undefined behavior in bit shift for CAP_TO_MASK

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[ Upstream commit 46653972e3ea64f79e7f8ae3aa41a4d3fdb70a13 ]

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>

Fixes: e338d263a7 ("Add 64-bit capability support to the kernel")
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Acked-by: Andrew G. Morgan <morgan@kernel.org>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Gaosheng Cui 2022-10-31 19:25:36 +08:00 committed by Greg Kroah-Hartman
parent 08c3d22f10
commit 5661f111a1
1 changed files with 1 additions and 1 deletions
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include/uapi/linux/capability.h
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@ -376,7 +376,7 @@ struct vfs_ns_cap_data {
*/
#define CAP_TO_INDEX(x) ((x) >> 5) /* 1 << 5 == bits in __u32 */
#define CAP_TO_MASK(x) (1 << ((x) & 31)) /* mask for indexed __u32 */
#define CAP_TO_MASK(x) (1U << ((x) & 31)) /* mask for indexed __u32 */
#endif /* _UAPI_LINUX_CAPABILITY_H */