[PATCH] Initialized initrd_ctx so we don't free a random pointer from the stack.

[Peter Jones <pjones@redhat.com>]

Currently, if "linux" fails, the "goto fail;" in grub_cmd_initrd sends us
into grub_initrd_close() without grub_initrd_init() being called, and thus
it never clears initrd_ctx->components.  grub_initrd_close() then frees that
address, which is stale data from the stack.  If the stack happens to have a
stale *address* there that matches a recent allocation, then you'll get a
double free later.

So initialize the memory up front.

Signed-off-by: Peter Jones <pjones@redhat.com>
---
 grub-core/loader/arm/linux.c              | 2 +-
 grub-core/loader/arm64/linux.c            | 2 +-
 grub-core/loader/i386/linux.c             | 2 +-
 grub-core/loader/i386/pc/linux.c          | 2 +-
 grub-core/loader/ia64/efi/linux.c         | 2 +-
 grub-core/loader/mips/linux.c             | 2 +-
 grub-core/loader/powerpc/ieee1275/linux.c | 2 +-
 grub-core/loader/sparc64/ieee1275/linux.c | 2 +-
 8 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/grub-core/loader/arm/linux.c b/grub-core/loader/arm/linux.c
index e6770d9..62cbe75 100644
--- a/grub-core/loader/arm/linux.c
+++ b/grub-core/loader/arm/linux.c
@@ -396,7 +396,7 @@ grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
 {
   grub_file_t file;
   grub_size_t size = 0;
-  struct grub_linux_initrd_context initrd_ctx;
+  struct grub_linux_initrd_context initrd_ctx = { 0, };
 
   if (argc == 0)
     return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
diff --git a/grub-core/loader/arm64/linux.c b/grub-core/loader/arm64/linux.c
index f1d10a1..0dc144e 100644
--- a/grub-core/loader/arm64/linux.c
+++ b/grub-core/loader/arm64/linux.c
@@ -328,7 +328,7 @@ static grub_err_t
 grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
 		 int argc, char *argv[])
 {
-  struct grub_linux_initrd_context initrd_ctx;
+  struct grub_linux_initrd_context initrd_ctx = { 0, };
   int initrd_size, initrd_pages;
   void *initrd_mem = NULL;
 
diff --git a/grub-core/loader/i386/linux.c b/grub-core/loader/i386/linux.c
index 31fb91e..2ae1763 100644
--- a/grub-core/loader/i386/linux.c
+++ b/grub-core/loader/i386/linux.c
@@ -1050,7 +1050,7 @@ grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
   grub_addr_t addr_min, addr_max;
   grub_addr_t addr;
   grub_err_t err;
-  struct grub_linux_initrd_context initrd_ctx;
+  struct grub_linux_initrd_context initrd_ctx = { 0, };
 
   if (argc == 0)
     {
diff --git a/grub-core/loader/i386/pc/linux.c b/grub-core/loader/i386/pc/linux.c
index 672c013..b481e46 100644
--- a/grub-core/loader/i386/pc/linux.c
+++ b/grub-core/loader/i386/pc/linux.c
@@ -388,7 +388,7 @@ grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
   grub_uint8_t *initrd_chunk;
   grub_addr_t initrd_addr;
   grub_err_t err;
-  struct grub_linux_initrd_context initrd_ctx;
+  struct grub_linux_initrd_context initrd_ctx = { 0, };
 
   if (argc == 0)
     {
diff --git a/grub-core/loader/ia64/efi/linux.c b/grub-core/loader/ia64/efi/linux.c
index 87ac49f..eb78e6e 100644
--- a/grub-core/loader/ia64/efi/linux.c
+++ b/grub-core/loader/ia64/efi/linux.c
@@ -568,7 +568,7 @@ static grub_err_t
 grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
 		 int argc, char *argv[])
 {
-  struct grub_linux_initrd_context initrd_ctx;
+  struct grub_linux_initrd_context initrd_ctx = { 0, };
 
   if (argc == 0)
     {
diff --git a/grub-core/loader/mips/linux.c b/grub-core/loader/mips/linux.c
index ef64a5b..4a3e8c5 100644
--- a/grub-core/loader/mips/linux.c
+++ b/grub-core/loader/mips/linux.c
@@ -415,7 +415,7 @@ grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
   void *initrd_src;
   grub_addr_t initrd_dest;
   grub_err_t err;
-  struct grub_linux_initrd_context initrd_ctx;
+  struct grub_linux_initrd_context initrd_ctx = { 0, };
 
   if (argc == 0)
     return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
diff --git a/grub-core/loader/powerpc/ieee1275/linux.c b/grub-core/loader/powerpc/ieee1275/linux.c
index 4a14f66..787d7dc 100644
--- a/grub-core/loader/powerpc/ieee1275/linux.c
+++ b/grub-core/loader/powerpc/ieee1275/linux.c
@@ -333,7 +333,7 @@ grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
   grub_size_t size = 0;
   grub_addr_t first_addr;
   grub_addr_t addr;
-  struct grub_linux_initrd_context initrd_ctx;
+  struct grub_linux_initrd_context initrd_ctx = { 0, };
 
   if (argc == 0)
     {
diff --git a/grub-core/loader/sparc64/ieee1275/linux.c b/grub-core/loader/sparc64/ieee1275/linux.c
index de6ee2f..c5e8dfa 100644
--- a/grub-core/loader/sparc64/ieee1275/linux.c
+++ b/grub-core/loader/sparc64/ieee1275/linux.c
@@ -373,7 +373,7 @@ grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
   grub_addr_t paddr;
   grub_addr_t addr;
   int ret;
-  struct grub_linux_initrd_context initrd_ctx;
+  struct grub_linux_initrd_context initrd_ctx = { 0, };
 
   if (argc == 0)
     {
-- 
1.9.3