x86: tls prevent_tail_call (3d00daf4) · Commits · 戴 / test

Fix a kernel bug (vmware boot problem) reported by Tomasz Grobelny, which occurs with certain .config variants and gccs. The x86 TLS cleanup in commit made the sys_set_thread_area and sys_get_thread_area functions ripe for tail call optimization. If the compiler chooses to use it for them, it can clobber the user trap frame because these are asmlinkage functions. Reported-by:

Tomasz Grobelny <tomasz@grobelny.oswiecenia.net> Signed-off-by:

Roland McGrath <roland@redhat.com> Signed-off-by:

Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/tls.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -91,7 +91,9 @@ int do_set_thread_area(struct task_struct *p, int idx,

		asmlinkage int sys_set_thread_area(struct user_desc __user *u_info)
		{
		return do_set_thread_area(current, -1, u_info, 1);
		int ret = do_set_thread_area(current, -1, u_info, 1);
		prevent_tail_call(ret);
		return ret;
		}


		@@ -139,7 +141,9 @@ int do_get_thread_area(struct task_struct *p, int idx,

		asmlinkage int sys_get_thread_area(struct user_desc __user *u_info)
		{
		return do_get_thread_area(current, -1, u_info);
		int ret = do_get_thread_area(current, -1, u_info);
		prevent_tail_call(ret);
		return ret;
		}

		int regset_tls_active(struct task_struct *target,

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