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latent_entropy: Fix wrong gcc code generation with 64 bit variables

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The stack frame size could grow too large when the plugin used long long
on 32-bit architectures when the given function had too many basic blocks.

The gcc warning was:

drivers/pci/hotplug/ibmphp_ebda.c: In function 'ibmphp_access_ebda':
drivers/pci/hotplug/ibmphp_ebda.c:409:1: warning: the frame size of 1108 bytes is larger than 1024 bytes [-Wframe-larger-than=]

This switches latent_entropy from u64 to unsigned long.

Thanks to PaX Team and Emese Revfy for the patch.

Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2016-10-19 00:08:04 +02:00
parent da7389ac6c
commit 58bea4144d
2 changed files with 10 additions and 11 deletions
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2
mm/page_alloc.c
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@ -92,7 +92,7 @@ int _node_numa_mem_[MAX_NUMNODES];
#endif
#ifdef CONFIG_GCC_PLUGIN_LATENT_ENTROPY
volatile u64 latent_entropy __latent_entropy;
volatile unsigned long latent_entropy __latent_entropy;
EXPORT_SYMBOL(latent_entropy);
#endif

19
scripts/gcc-plugins/latent_entropy_plugin.c
View File

@ -340,7 +340,7 @@ static enum tree_code get_op(tree *rhs)
break;
}
if (rhs)
*rhs = build_int_cstu(unsigned_intDI_type_node, random_const);
*rhs = build_int_cstu(long_unsigned_type_node, random_const);
return op;
}
@ -372,7 +372,7 @@ static void __perturb_latent_entropy(gimple_stmt_iterator *gsi,
enum tree_code op;
/* 1. create temporary copy of latent_entropy */
temp = create_var(unsigned_intDI_type_node, "tmp_latent_entropy");
temp = create_var(long_unsigned_type_node, "temp_latent_entropy");
/* 2. read... */
add_referenced_var(latent_entropy_decl);
@ -459,13 +459,13 @@ static void init_local_entropy(basic_block bb, tree local_entropy)
gsi_insert_before(&gsi, call, GSI_NEW_STMT);
update_stmt(call);
udi_frame_addr = fold_convert(unsigned_intDI_type_node, frame_addr);
udi_frame_addr = fold_convert(long_unsigned_type_node, frame_addr);
assign = gimple_build_assign(local_entropy, udi_frame_addr);
gsi_insert_after(&gsi, assign, GSI_NEW_STMT);
update_stmt(assign);
/* 3. create temporary copy of latent_entropy */
tmp = create_var(unsigned_intDI_type_node, "tmp_latent_entropy");
tmp = create_var(long_unsigned_type_node, "temp_latent_entropy");
/* 4. read the global entropy variable into local entropy */
add_referenced_var(latent_entropy_decl);
@ -480,7 +480,7 @@ static void init_local_entropy(basic_block bb, tree local_entropy)
update_stmt(assign);
rand_cst = get_random_const();
rand_const = build_int_cstu(unsigned_intDI_type_node, rand_cst);
rand_const = build_int_cstu(long_unsigned_type_node, rand_cst);
op = get_op(NULL);
assign = create_assign(op, local_entropy, local_entropy, rand_const);
gsi_insert_after(&gsi, assign, GSI_NEW_STMT);
@ -529,7 +529,7 @@ static unsigned int latent_entropy_execute(void)
}
/* 1. create the local entropy variable */
local_entropy = create_var(unsigned_intDI_type_node, "local_entropy");
local_entropy = create_var(long_unsigned_type_node, "local_entropy");
/* 2. initialize the local entropy variable */
init_local_entropy(bb, local_entropy);
@ -561,10 +561,9 @@ static void latent_entropy_start_unit(void *gcc_data __unused,
if (in_lto_p)
return;
/* extern volatile u64 latent_entropy */
gcc_assert(TYPE_PRECISION(long_long_unsigned_type_node) == 64);
quals = TYPE_QUALS(long_long_unsigned_type_node) | TYPE_QUAL_VOLATILE;
type = build_qualified_type(long_long_unsigned_type_node, quals);
/* extern volatile unsigned long latent_entropy */
quals = TYPE_QUALS(long_unsigned_type_node) | TYPE_QUAL_VOLATILE;
type = build_qualified_type(long_unsigned_type_node, quals);
id = get_identifier("latent_entropy");
latent_entropy_decl = build_decl(UNKNOWN_LOCATION, VAR_DECL, id, type);