On 2018-03-19 20:22, Andreas Reichel wrote: > On Mon, Mar 19, 2018 at 06:38:43PM +0800, Jan Kiszka wrote: >> On 2018-03-13 01:10, [ext] Andreas J. Reichel wrote: >>> From: Andreas Reichel <[email protected]> >>> >>> If a non-existing user variable is requested and a NULL-buffer is >>> provided, the getter maps an invalid memory area to retrieve the needed >>> buffer size. >>> Fix this by checking if the data pointer is valid first before mapping >>> anything and furthermore don't call the mapper if the variable is not >>> found. >>> >>> Signed-off-by: Andreas Reichel <[email protected]> >>> --- >>> env/env_api_fat.c | 3 +++ >>> env/uservars.c | 4 ++++ >>> 2 files changed, 7 insertions(+) >>> >>> diff --git a/env/env_api_fat.c b/env/env_api_fat.c >>> index 1705cb9..a86c05d 100644 >>> --- a/env/env_api_fat.c >>> +++ b/env/env_api_fat.c >>> @@ -287,6 +287,9 @@ int bgenv_get(BGENV *env, char *key, uint64_t *type, >>> void *data, >>> uint8_t *u; >>> uint32_t size; >>> u = bgenv_find_uservar(env->data->userdata, key); >>> + if (!u) { >>> + return -EINVAL; >>> + } >>> bgenv_map_uservar(u, NULL, NULL, NULL, NULL, &size); >>> return size; >>> } >>> diff --git a/env/uservars.c b/env/uservars.c >>> index eff1cf8..e1e2334 100644 >>> --- a/env/uservars.c >>> +++ b/env/uservars.c >>> @@ -38,6 +38,10 @@ void bgenv_map_uservar(uint8_t *udata, char **key, >>> uint64_t *type, uint8_t **val >>> uint64_t *var_type; >>> uint8_t *data; >>> >>> + if (!udata) { >>> + return; >>> + } >>> + >> >> Did you check that this does not paper over an issue of the caller (like >> the one you fixes with the first hunk)? >> > This is intended. > Both are usable API functions and they should be robust. That one is > called by the other does not change this.
If udata == NULL is a bug of the caller (rather than a valid mode of operation), that bug should be reported rather than swallowed. If you consider that like free(NULL), then it's a different thing, but this function does not look like that at all. So, please do not drop errors under the table. Jan -- You received this message because you are subscribed to the Google Groups "EFI Boot Guard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/efibootguard-dev/bb638665-921f-5a7f-3ecf-fabe29665220%40siemens.com. For more options, visit https://groups.google.com/d/optout.
