diff mbox series

[dwarves,v4,2/4] btf_encoder: explicitly check addr/size for u32 overflow

Message ID 20241004172631.629870-3-stephen.s.brennan@oracle.com (mailing list archive)
State Not Applicable
Delegated to: BPF
Headers show
Series Emit global variables in BTF | expand

Checks

Context Check Description
netdev/tree_selection success Not a local patch

Commit Message

Stephen Brennan Oct. 4, 2024, 5:26 p.m. UTC 
The addr is a uint64_t, and depending on the size of a data section,
there's no guarantee that it fits into a uint32_t, even after
subtracting out the section start address. Similarly, the variable size
is a size_t which could exceed a uint32_t. Check both for overflow, and
if found, skip the variable with an error message. Use explicit casts
when we cast to uint32_t so it's plain to see that this is happening.

Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
---
 btf_encoder.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/btf_encoder.c b/btf_encoder.c
index 61e9ece..5586cd8 100644
--- a/btf_encoder.c
+++ b/btf_encoder.c
@@ -2253,9 +2253,16 @@  static int btf_encoder__encode_cu_variables(struct btf_encoder *encoder)
 
 		tag = cu__type(cu, var->ip.tag.type);
 		size = tag__size(tag, cu);
-		if (size == 0) {
+		if (size == 0 || size > UINT32_MAX) {
 			if (encoder->verbose)
-				fprintf(stderr, "Ignoring zero-sized per-CPU variable '%s'...\n", name);
+				fprintf(stderr, "Ignoring %s-sized per-CPU variable '%s'...\n",
+					size == 0 ? "zero" : "over", name);
+			continue;
+		}
+		if (addr > UINT32_MAX) {
+			if (encoder->verbose)
+				fprintf(stderr, "Ignoring variable '%s' - its offset %zu doesn't fit in a u32\n",
+					name, addr);
 			continue;
 		}
 
@@ -2288,7 +2295,7 @@  static int btf_encoder__encode_cu_variables(struct btf_encoder *encoder)
 		 * add a BTF_VAR_SECINFO in encoder->percpu_secinfo, which will be added into
 		 * encoder->types later when we add BTF_VAR_DATASEC.
 		 */
-		id = btf_encoder__add_var_secinfo(encoder, id, addr, size);
+		id = btf_encoder__add_var_secinfo(encoder, id, (uint32_t)addr, (uint32_t)size);
 		if (id < 0) {
 			fprintf(stderr, "error: failed to encode section info for variable '%s' at addr 0x%" PRIx64 "\n",
 			        name, addr);