From c65ff27d7158ca31cca0bb4b77a515c8a5bddced Mon Sep 17 00:00:00 2001 From: Alejandro Vallejo Date: Thu, 19 Jun 2025 13:42:04 +0200 Subject: [PATCH] xen/dt: Remove loop in dt_read_number() The DT spec declares only two number types for a property: u32 and u64, as per Table 2.3 in Section 2.2.4. Remove unbounded loop and replace with a switch statement. Default to a size of 1 cell in the nonsensical size case, with a warning printed on the Xen console. Suggested-by: Daniel P. Smith" Signed-off-by: Alejandro Vallejo Reviewed-by: Stefano Stabellini --- xen/include/xen/device_tree.h | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h index 75017e4266..d2de7c3a13 100644 --- a/xen/include/xen/device_tree.h +++ b/xen/include/xen/device_tree.h @@ -261,10 +261,22 @@ void intc_dt_preinit(void); /* Helper to read a big number; size is in cells (not bytes) */ static inline u64 dt_read_number(const __be32 *cell, int size) { - u64 r = 0; + u64 r = be32_to_cpu(*cell); + + switch ( size ) + { + case 1: + break; + case 2: + r = (r << 32) | be32_to_cpu(cell[1]); + break; + default: + /* Nonsensical size. default to 1 */ + printk(XENLOG_ERR "dt_read_number(,%d) bad size\n", size); + ASSERT_UNREACHABLE(); + break; + }; - while ( size-- ) - r = (r << 32) | be32_to_cpu(*(cell++)); return r; }