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| author | Benjamin Berg <benjamin.berg@intel.com> | 2024-12-17 21:27:44 +0100 |
|---|---|---|
| committer | Richard Weinberger <richard@nod.at> | 2025-02-12 23:40:38 +0100 |
| commit | 8891b176d350ec5ea9a39c6ef4c99bd63d68e64c (patch) | |
| tree | ff78ecd550af765090dd95cf9a26ea7cbeb321ab /arch/um | |
| parent | 5298b7cffa8461009a4410f4e23f1c50ade39182 (diff) | |
| download | linux-stable-8891b176d350ec5ea9a39c6ef4c99bd63d68e64c.tar.gz linux-stable-8891b176d350ec5ea9a39c6ef4c99bd63d68e64c.tar.bz2 linux-stable-8891b176d350ec5ea9a39c6ef4c99bd63d68e64c.zip | |
um: avoid copying FP state from init_task
The init_task instance of struct task_struct is statically allocated and
does not contain the dynamic area for the userspace FP registers. As
such, limit the copy to the valid area of init_task and fill the rest
with zero.
Note that the FP state is only needed for userspace, and as such it is
entirely reasonable for init_task to not contain it.
Reported-by: Brian Norris <briannorris@chromium.org>
Closes: https://lore.kernel.org/Z1ySXmjZm-xOqk90@google.com
Fixes: 3f17fed21491 ("um: switch to regset API and depend on XSTATE")
Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20241217202745.1402932-3-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'arch/um')
| -rw-r--r-- | arch/um/kernel/process.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c index e5a2d4d897e0..0cd6fad3d908 100644 --- a/arch/um/kernel/process.c +++ b/arch/um/kernel/process.c @@ -191,7 +191,15 @@ void initial_thread_cb(void (*proc)(void *), void *arg) int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) { - memcpy(dst, src, arch_task_struct_size); + /* init_task is not dynamically sized (missing FPU state) */ + if (unlikely(src == &init_task)) { + memcpy(dst, src, sizeof(init_task)); + memset((void *)dst + sizeof(init_task), 0, + arch_task_struct_size - sizeof(init_task)); + } else { + memcpy(dst, src, arch_task_struct_size); + } + return 0; } |