5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Finn Thain fthain@linux-m68k.org
[ Upstream commit 09b3d870faa7bc3e96c0978ab3cf4e96e4b15571 ]
Stan Johnson recently reported a failure from the 'dump' command:
DUMP: Date of this level 0 dump: Fri Aug 9 23:37:15 2024 DUMP: Dumping /dev/sda (an unlisted file system) to /dev/null DUMP: Label: none DUMP: Writing 10 Kilobyte records DUMP: mapping (Pass I) [regular files] DUMP: mapping (Pass II) [directories] DUMP: estimated 3595695 blocks. DUMP: Context save fork fails in parent 671
The dump program uses the clone syscall with the CLONE_IO flag, that is, flags == 0x80000000. When that value is promoted from long int to u64 by m68k_clone(), it undergoes sign-extension. The new value includes CLONE_INTO_CGROUP so the validation in cgroup_css_set_fork() fails and the syscall returns -EBADF. Avoid sign-extension by casting to u32.
Reported-by: Stan Johnson userm57@yahoo.com Closes: https://lists.debian.org/debian-68k/2024/08/msg00000.html Fixes: 6aabc1facdb2 ("m68k: Implement copy_thread_tls()") Signed-off-by: Finn Thain fthain@linux-m68k.org Reviewed-by: Geert Uytterhoeven geert@linux-m68k.org Link: https://lore.kernel.org/3463f1e5d4e95468dc9f3368f2b78ffa7b72199b.1723335149.... Signed-off-by: Geert Uytterhoeven geert@linux-m68k.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/m68k/kernel/process.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/m68k/kernel/process.c b/arch/m68k/kernel/process.c index 1ab692b952cd6..32427aa131667 100644 --- a/arch/m68k/kernel/process.c +++ b/arch/m68k/kernel/process.c @@ -116,7 +116,7 @@ asmlinkage int m68k_clone(struct pt_regs *regs) { /* regs will be equal to current_pt_regs() */ struct kernel_clone_args args = { - .flags = regs->d1 & ~CSIGNAL, + .flags = (u32)(regs->d1) & ~CSIGNAL, .pidfd = (int __user *)regs->d3, .child_tid = (int __user *)regs->d4, .parent_tid = (int __user *)regs->d3,