coredump: Proactively round up to kmalloc bucket size

PATCH Superseded Kees Cook 1 participant 1 message Oct 18, 2022 VFS

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Kees Cook

author

2022-10-18 09:07 UTC #0 lore raw

PATCH 1/1 coredump: Proactively round up to kmalloc bucket size

Instead of discovering the kmalloc bucket size _after_ allocation, round up proactively so the allocation is explicitly made for the full size, allowing the compiler to correctly reason about the resulting size of the buffer through the existing __alloc_size() hint.

Cc Alexander Viro <[email protected]>

Cc [email protected]

Signed-off-by Kees Cook <[email protected]>

---
 fs/coredump.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

fs/coredump.c +5 -2

index 7bad7785e8e6..97eaee325251 100644
@@ -68,7 +68,10 @@ struct core_name {
 
 static int expand_corename(struct core_name *cn, int size)
 {
-	char *corename = krealloc(cn->corename, size, GFP_KERNEL);
+	char *corename;
+
+	size = kmalloc_size_roundup(size);
+	corename = krealloc(cn->corename, size, GFP_KERNEL);
 
 	if (!corename)
 		return -ENOMEM;

@@ -76,7 +79,7 @@ static int expand_corename(struct core_name *cn, int size)
 	if (size > core_name_size) /* racy but harmless */
 		core_name_size = size;
 
-	cn->size = ksize(corename);
+	cn->size = size;
 	cn->corename = corename;
 	return 0;
 }

Signature · 1 line

2.34.1