[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH 10/21] hw/core: Fix latent fit_load_fdt() error handling bug
From: |
Markus Armbruster |
Subject: |
Re: [PATCH 10/21] hw/core: Fix latent fit_load_fdt() error handling bug |
Date: |
Fri, 06 Dec 2019 08:46:38 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) |
Vladimir Sementsov-Ogievskiy <address@hidden> writes:
> 30.11.2019 22:42, Markus Armbruster wrote:
>> fit_load_fdt() recovers from fit_image_addr() failing with ENOENT.
>> Except it doesn't when its @errp argument is &error_fatal or
>> &error_abort, because it blindly passes @errp to fit_image_addr().
>> Messed up in commit 3eb99edb48 "loader-fit: Wean off error_printf()".
>>
>> The bug can't bite as no caller actually passes &error_fatal or
>> &error_abort. Fix it anyway.
>>
>> Signed-off-by: Markus Armbruster <address@hidden>
>
> Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>
>
> Hmm, actually it makes my
> "[PATCH v7 01/21] hw/core/loader-fit: fix freeing errp in fit_load_fdt"
> unnecessary. If you want you may drop my 01 (as it covers less problems),
Yes.
> and in this case you may note in your cover letter, that
> errp = NULL is broken here too (may be nobady pass it?),
You're right, null @errp is wrong, too.
> and normal errp is handled wrong, as *errp doesn't set to NULL after
> error_free(*errp)
Yes, that's wrong, too. fit_load_fdt() itself doesn't use *errp after
freeing it, but it sets a trap for its callers.
> (still, the only caller rely on return value more than on
> err, so the problem can't be triggered with current code)
True.
New commit message (based on v2's):
hw/core: Fix fit_load_fdt() error API violations
fit_load_fdt() passes @errp to fit_image_addr(), then recovers from
ENOENT failures. Passing @errp is wrong, because it works only as
long as @errp is neither @error_fatal nor @error_abort. Error
recovery dereferences @errp. That's also wrong; see the big comment
in error.h. Error recovery can leave *errp pointing to a freed
Error object. Wrong, it must be null on success. Messed up in
commit 3eb99edb48 "loader-fit: Wean off error_printf()".
No caller actually passes such values, or uses *errp on success.
Fix anyway: splice in a local Error *err, and error_propagate().
Signed-off-by: Markus Armbruster <address@hidden>
Okay?
>
>> ---
>> hw/core/loader-fit.c | 15 ++++++++-------
>> 1 file changed, 8 insertions(+), 7 deletions(-)
>>
>> diff --git a/hw/core/loader-fit.c b/hw/core/loader-fit.c
>> index 953b16bc82..c465921b8f 100644
>> --- a/hw/core/loader-fit.c
>> +++ b/hw/core/loader-fit.c
>> @@ -178,11 +178,12 @@ static int fit_load_fdt(const struct fit_loader *ldr,
>> const void *itb,
>> int cfg, void *opaque, const void *match_data,
>> hwaddr kernel_end, Error **errp)
>> {
>> + Error *err = NULL;
>> const char *name;
>> const void *data;
>> const void *load_data;
>> hwaddr load_addr;
>> - int img_off, err;
>> + int img_off;
>> size_t sz;
>> int ret;
>>
>> @@ -197,13 +198,13 @@ static int fit_load_fdt(const struct fit_loader *ldr,
>> const void *itb,
>> return -EINVAL;
>> }
>>
>> - err = fit_image_addr(itb, img_off, "load", &load_addr, errp);
>> - if (err == -ENOENT) {
>> + ret = fit_image_addr(itb, img_off, "load", &load_addr, &err);
>> + if (ret == -ENOENT) {
>> load_addr = ROUND_UP(kernel_end, 64 * KiB) + (10 * MiB);
>> - error_free(*errp);
>> - } else if (err) {
>> - error_prepend(errp, "unable to read FDT load address from FIT: ");
>> - ret = err;
>> + error_free(err);
>> + } else if (ret) {
>> + error_propagate_prepend(errp, err,
>> + "unable to read FDT load address from FIT:
>> ");
>> goto out;
>> }
>>
>>
>
> So much attention to that function :)
>
> I'd also propose the following:
>
> diff --git a/hw/core/loader-fit.c b/hw/core/loader-fit.c
> index c465921b8f..2c9efeef7a 100644
> --- a/hw/core/loader-fit.c
> +++ b/hw/core/loader-fit.c
> @@ -180,8 +180,8 @@ static int fit_load_fdt(const struct fit_loader *ldr,
> const void *itb,
> {
> Error *err = NULL;
> const char *name;
> - const void *data;
> - const void *load_data;
> + void *data;
> + void *load_data;
> hwaddr load_addr;
> int img_off;
> size_t sz;
> @@ -218,9 +218,9 @@ static int fit_load_fdt(const struct fit_loader *ldr,
> const void *itb,
>
> ret = 0;
> out:
> - g_free((void *) data);
> + g_free(data);
> if (data != load_data) {
> - g_free((void *) load_data);
> + g_free(load_data);
> }
> return ret;
> }
>
>
> Or, even better:
>
> --- a/hw/core/loader-fit.c
> +++ b/hw/core/loader-fit.c
> @@ -180,7 +180,8 @@ static int fit_load_fdt(const struct fit_loader *ldr,
> const void *itb,
> {
> Error *err = NULL;
> const char *name;
> - const void *data;
> + g_autofree void *data = NULL;
> + g_autofree void *fdt_filter_data = NULL;
> const void *load_data;
> hwaddr load_addr;
> int img_off;
> @@ -202,27 +203,23 @@ static int fit_load_fdt(const struct fit_loader *ldr,
> const void *itb,
> if (ret == -ENOENT) {
> load_addr = ROUND_UP(kernel_end, 64 * KiB) + (10 * MiB);
> error_free(err);
> + return 0;
> } else if (ret) {
> error_propagate_prepend(errp, err,
> "unable to read FDT load address from FIT:
> ");
> - goto out;
> + return ret;
> }
>
> if (ldr->fdt_filter) {
> - load_data = ldr->fdt_filter(opaque, data, match_data, &load_addr);
> + load_data = fdt_filter_data =
> + ldr->fdt_filter(opaque, data, match_data, &load_addr);
> }
>
> load_addr = ldr->addr_to_phys(opaque, load_addr);
> sz = fdt_totalsize(load_data);
> rom_add_blob_fixed(name, load_data, sz, load_addr);
>
> - ret = 0;
> -out:
> - g_free((void *) data);
> - if (data != load_data) {
> - g_free((void *) load_data);
> - }
> - return ret;
> + return 0;
> }
Looks like a sensible separate cleanup patch to me. Care to post it?
Thanks!