[PATCH 1/1] net: phy: Fix signed shift overflow

* [PATCH 1/1] net: phy: Fix signed shift overflow
@ 2024-01-04  4:26 Heinrich Schuchardt
  2024-03-28 15:09 ` Tom Rini
  0 siblings, 1 reply; 2+ messages in thread
From: Heinrich Schuchardt @ 2024-01-04  4:26 UTC (permalink / raw)
  To: Joe Hershberger; +Cc: Ramon Fried, u-boot, Eugeniu Rosca, Heinrich Schuchardt

From: Eugeniu Rosca <erosca@de.adit-jv.com>

Booting R-Car Gen3 arm64 U-Boot with CONFIG_UBSAN=y resulted in:

 =====================================================================
 UBSAN: Undefined behaviour in drivers/net/phy/phy.c:728:19
 left shift of 1 by 31 places cannot be represented in type 'int'
 =====================================================================

Fix it by appending the UL suffix to the numeric literal. While at it,
convert the type of "addr" variable from signed to unsigned, to protect
against shifting the numeric literal by a negative value (which would
lead to yet another undefined behavior).

Fixes: 1adb406b0141 ("phy: add phy_find_by_mask/phy_connect_dev")
Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>

* Using U-suffix for integer is sufficient.
* ffs() of non-zero value cannot be 0. But addr being unsigned is
* preferable.
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
---
 drivers/net/phy/phy.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index 63b3e46f10..f39ca942f6 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -642,12 +642,12 @@ static struct phy_device *search_for_existing_phy(struct mii_dev *bus,
 {
 	/* If we have one, return the existing device, with new interface */
 	while (phy_mask) {
-		int addr = ffs(phy_mask) - 1;
+		unsigned int addr = ffs(phy_mask) - 1;
 
 		if (bus->phymap[addr])
 			return bus->phymap[addr];
 
-		phy_mask &= ~(1 << addr);
+		phy_mask &= ~(1U << addr);
 	}
 	return NULL;
 }
-- 
2.43.0


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