[PATCH] module: fix reference to mod->percpu after freeing module.
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From: Rusty Russell on 31 May 2010 06:30 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" <rjw(a)sisk.pl> Signed-off-by: Rusty Russell <rusty(a)rustcorp.com.au> Cc: Tejun Heo <tj(a)kernel.org> Cc: Masami Hiramatsu <mhiramat(a)redhat.com> Tested-by: "Rafael J. Wysocki" <rjw(a)sisk.pl> --- kernel/module.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/module.c b/kernel/module.c --- a/kernel/module.c +++ b/kernel/module.c @@ -2031,6 +2031,7 @@ static noinline struct module *load_modu long err = 0; void *ptr = NULL; /* Stops spurious gcc warning */ unsigned long symoffs, stroffs, *strmap; + void __percpu *percpu; mm_segment_t old_fs; @@ -2175,6 +2176,8 @@ static noinline struct module *load_modu 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 @@ -2480,7 +2483,7 @@ static noinline struct module *load_modu 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); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |