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[efi] Create a copy of the system flattened device tree, if present 

EFI configuration tables may be freed at any time, and there is no way
to be notified when the table becomes invalidated.  Create a copy of
the system flattened device tree (if present), so that we do not risk
being left with an invalid pointer.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
pull/1437/head
Michael Brown 2025-03-28 14:10:55 +00:00
parent 3860313dd5
commit 666929e311
3 changed files with 15 additions and 5 deletions
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3
src/core/fdt.c
View File

@ -456,8 +456,7 @@ int fdt_mac ( struct fdt *fdt, unsigned int offset,
* @v max_len Maximum device tree length
* @ret rc Return status code
*/
int fdt_parse ( struct fdt *fdt, const struct fdt_header *hdr,
size_t max_len ) {
int fdt_parse ( struct fdt *fdt, struct fdt_header *hdr, size_t max_len ) {
const uint8_t *end;
/* Sanity check */

6
src/include/ipxe/fdt.h
View File

@ -78,9 +78,9 @@ struct fdt {
/** Tree data */
union {
/** Tree header */
const struct fdt_header *hdr;
struct fdt_header *hdr;
/** Raw data */
const void *raw;
void *raw;
};
/** Length of tree */
size_t len;
@ -107,7 +107,7 @@ extern int fdt_u64 ( struct fdt *fdt, unsigned int offset, const char *name,
uint64_t *value );
extern int fdt_mac ( struct fdt *fdt, unsigned int offset,
struct net_device *netdev );
extern int fdt_parse ( struct fdt *fdt, const struct fdt_header *hdr,
extern int fdt_parse ( struct fdt *fdt, struct fdt_header *hdr,
size_t max_len );
#endif /* _IPXE_FDT_H */

11
src/interface/efi/efi_fdt.c
View File

@ -44,6 +44,8 @@ EFI_USE_TABLE ( FDT_TABLE, &efi_fdt, 0 );
*
*/
static void efi_fdt_init ( void ) {
EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
EFI_STATUS efirc;
int rc;
/* Do nothing if no configuration table is present */
@ -59,6 +61,15 @@ static void efi_fdt_init ( void ) {
strerror ( rc ) );
return;
}
/* Create copy, since table may be removed at any time */
if ( ( efirc = bs->AllocatePool ( EfiBootServicesData, sysfdt.len,
&sysfdt.raw ) ) != 0 ) {
DBGC ( &efi_fdt, "EFIFDT could not create copy\n" );
sysfdt.len = 0;
return;
}
memcpy ( sysfdt.raw, efi_fdt, sysfdt.len );
}
/** EFI Flattened Device Tree initialisation function */