CVE-2025-71102
scs: fix a wrong parameter in __scs_magic
In the Linux kernel, the following vulnerability has been resolved:
scs: fix a wrong parameter in __scs_magic
__scs_magic() needs a 'void *' variable, but a 'struct task_struct *' is
given. 'task_scs(tsk)' is the starting address of the task's shadow call
stack, and '__scs_magic(task_scs(tsk))' is the end address of the task's
shadow call stack. Here should be '__scs_magic(task_scs(tsk))'.
The user-visible effect of this bug is that when CONFIG_DEBUG_STACK_USAGE
is enabled, the shadow call stack usage checking function
(scs_check_usage) would scan an incorrect memory range. This could lead
1. **Inaccurate stack usage reporting**: The function would calculate
wrong usage statistics for the shadow call stack, potentially showing
incorrect value in kmsg.
2. **Potential kernel crash**: If the value of __scs_magic(tsk)is
greater than that of __scs_magic(task_scs(tsk)), the for loop may
access unmapped memory, potentially causing a kernel panic. However,
this scenario is unlikely because task_struct is allocated via the slab
allocator (which typically returns lower addresses), while the shadow
call stack returned by task_scs(tsk) is allocated via vmalloc(which
typically returns higher addresses).
However, since this is purely a debugging feature
(CONFIG_DEBUG_STACK_USAGE), normal production systems should be not
unaffected. The bug only impacts developers and testers who are actively
debugging stack usage with this configuration enabled.
Affected products
Linux · LinuxWant to know if your infrastructure is exposed to this?
Talk to TrueHacking →References
https://git.kernel.org/stable/c/062774439d442882b44f5eab8c256ad3423ef284https://git.kernel.org/stable/c/08bd4c46d5e63b78e77f2605283874bbe868ab19https://git.kernel.org/stable/c/1727e8bd69103a68963a5613a0ddb6d8d37df5d3https://git.kernel.org/stable/c/57ba40b001be27786d0570dd292289df748b306bhttps://git.kernel.org/stable/c/9ef28943471a16e4f9646bc3e8e2de148e7d8d7bhttps://git.kernel.org/stable/c/a19fb3611e4c06624fc0f83ef19f4fb8d57d4751https://git.kernel.org/stable/c/cfdf6250b63b953b1d8e60814c8ca96c6f9d1c8c