From 293a7cfeedc2b2380a7c7274902323c3cf5f7575 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Mon, 31 May 2010 19:53:50 +0930 Subject: [PATCH] module: fix reference to mod->percpu after freeing module. Rafael sees a sometimes crash at precpu_modfree from kernel/module.c; it only occurred with another (since-reverted) patch, but that patch simply changed timing to uncover this bug, it was otherwise unrelated. The comment about the mod being freed is self-explanatory, but neither Tejun nor I read it. This bug was introduced in 259354deaa, after it had previously been fixed in 6e2b75740b. How embarrassing. Reported-by: "Rafael J. Wysocki" Signed-off-by: Rusty Russell Embarrassingly-Acked-by: Tejun Heo Cc: Masami Hiramatsu Tested-by: "Rafael J. Wysocki" Signed-off-by: Linus Torvalds --- kernel/module.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/module.c b/kernel/module.c index 333fbcc96978..d806e00e4450 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2014,6 +2014,7 @@ static noinline struct module *load_module(void __user *umod, long err = 0; void *ptr = NULL; /* Stops spurious gcc warning */ unsigned long symoffs, stroffs, *strmap; + void __percpu *percpu; mm_segment_t old_fs; @@ -2158,6 +2159,8 @@ static noinline struct module *load_module(void __user *umod, goto free_mod; sechdrs[pcpuindex].sh_flags &= ~(unsigned long)SHF_ALLOC; } + /* Keep this around for failure path. */ + percpu = mod_percpu(mod); /* Determine total sizes, and put offsets in sh_entsize. For now this is done generically; there doesn't appear to be any @@ -2463,7 +2466,7 @@ static noinline struct module *load_module(void __user *umod, module_free(mod, mod->module_core); /* mod will be freed with core. Don't access it beyond this line! */ free_percpu: - percpu_modfree(mod); + free_percpu(percpu); free_mod: kfree(args); kfree(strmap);