From: Ard Biesheuvel <ardb@kernel.org>
To: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Cc: jonathan.richardson@broadcom.com,
linux-efi <linux-efi@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] firmware/efi: Fix a use after bug in efi_mem_reserve_persistent
Date: Thu, 18 Mar 2021 19:17:40 +0100 [thread overview]
Message-ID: <CAMj1kXESeiozq=DAsYsKOP6DVEOQknPqUdam_LpRiPzhLhCCBg@mail.gmail.com> (raw)
In-Reply-To: <20210310083127.5784-1-lyl2019@mail.ustc.edu.cn>
On Wed, 10 Mar 2021 at 09:37, Lv Yunlong <lyl2019@mail.ustc.edu.cn> wrote:
>
> In the for loop in efi_mem_reserve_persistent(), prsv = rsv->next
> use the unmapped rsv. Use the unmapped pages will cause segment
> fault.
>
> Fixes: 18df7577adae6 ("efi/memreserve: deal with memreserve entries in unmapped memory")
> Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Queued as a fix, thanks.
> ---
> drivers/firmware/efi/efi.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index df3f9bcab581..4b7ee3fa9224 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -927,7 +927,7 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
> }
>
> /* first try to find a slot in an existing linked list entry */
> - for (prsv = efi_memreserve_root->next; prsv; prsv = rsv->next) {
> + for (prsv = efi_memreserve_root->next; prsv; ) {
> rsv = memremap(prsv, sizeof(*rsv), MEMREMAP_WB);
> index = atomic_fetch_add_unless(&rsv->count, 1, rsv->size);
> if (index < rsv->size) {
> @@ -937,6 +937,7 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
> memunmap(rsv);
> return efi_mem_reserve_iomem(addr, size);
> }
> + prsv = rsv->next;
> memunmap(rsv);
> }
>
> --
> 2.25.1
>
>
prev parent reply other threads:[~2021-03-18 18:18 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-10 8:31 [PATCH] firmware/efi: Fix a use after bug in efi_mem_reserve_persistent Lv Yunlong
2021-03-18 18:17 ` Ard Biesheuvel [this message]
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