On Mon, Feb 06, 2023 at 11:39:02AM +0100, Jakob Koschel wrote: > If &encl_mm->encl->mm_list does not contain the searched 'encl_mm', > 'tmp' will not point to a valid sgx_encl_mm struct. Please explain. Perhaps, extend with something like ", and can be turned into transient gadget." > > Since the code within the guarded block is just called when the element > is found, it can simply be moved into the list iterator. > Within the list iterator 'tmp' is guaranteed to point to a valid > element. > > Signed-off-by: Jakob Koschel <jkl820.git@xxxxxxxxx> > --- > Linus proposed to avoid any use of the list iterator variable after the > loop, in the attempt to move the list iterator variable declaration into > the marcro to avoid any potential misuse after the loop. > Using it in a pointer comparision after the loop is undefined behavior > and should be omitted if possible [1]. > > Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@xxxxxxxxxxxxxx/ [1] I would move all this to the commit message. It is useful information. > --- > arch/x86/kernel/cpu/sgx/encl.c | 10 ++++------ > 1 file changed, 4 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c > index 2a0e90fe2abc..db585b780141 100644 > --- a/arch/x86/kernel/cpu/sgx/encl.c > +++ b/arch/x86/kernel/cpu/sgx/encl.c > @@ -764,15 +764,13 @@ static void sgx_mmu_notifier_release(struct mmu_notifier *mn, > list_for_each_entry(tmp, &encl_mm->encl->mm_list, list) { > if (tmp == encl_mm) { > list_del_rcu(&encl_mm->list); > - break; > + spin_unlock(&encl_mm->encl->mm_lock); > + synchronize_srcu(&encl_mm->encl->srcu); > + mmu_notifier_put(mn); > + return; > } > } > spin_unlock(&encl_mm->encl->mm_lock); > - > - if (tmp == encl_mm) { > - synchronize_srcu(&encl_mm->encl->srcu); > - mmu_notifier_put(mn); > - } > } > > static void sgx_mmu_notifier_free(struct mmu_notifier *mn) > > --- > base-commit: d2d11f342b179f1894a901f143ec7c008caba43e > change-id: 20230206-sgx-use-after-iter-f584c1d64c87 > > Best regards, > -- > Jakob Koschel <jkl820.git@xxxxxxxxx> > BR, Jarkko
