xhci_alloc_command() allocates a command structure and, when the second argument is true, also allocates a completion structure. Currently, the error handling path in xhci_disable_slot() only frees the command structure using kfree(), causing the completion structure to leak.

Use xhci_free_command() instead of kfree(). xhci_free_command() correctly frees both the command structure and the associated completion structure. Since the command structure is allocated with zero-initialization, command->in_ctx is NULL and will not be erroneously freed by xhci_free_command().

This bug was found using an experimental static analysis tool we are developing. The tool is based on the LLVM framework and is specifically designed to detect memory management issues. It is currently under active development and not yet publicly available, but we plan to open-source it after our research is published.

The analysis was performed on Linux kernel v6.13-rc1.

We performed build testing on x86_64 with allyesconfig using GCC=11.4.0. Since triggering these error paths in xhci_disable_slot() requires specific hardware conditions or abnormal state, we were unable to construct a test case to reliably trigger these specific error paths at runtime.

Fixes: 7faac1953ed1 ("xhci: avoid race between disable slot command and host runtime suspend") CC: stable@vger.kernel.org Signed-off-by: Zilin Guan zilin@seu.edu.cn --- Changes in v2: - Add detailed information required by researcher guidelines. - Clarify the safety of using xhci_free_command() in this context. - Correct the Fixes tag to point to the commit that introduced this issue.

drivers/usb/host/xhci.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index 02c9bfe21ae2..f0beed054954 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -4137,7 +4137,7 @@ int xhci_disable_slot(struct xhci_hcd *xhci, u32 slot_id) if (state == 0xffffffff || (xhci->xhc_state & XHCI_STATE_DYING) || (xhci->xhc_state & XHCI_STATE_HALTED)) { spin_unlock_irqrestore(&xhci->lock, flags); - kfree(command); + xhci_free_command(xhci, command); return -ENODEV; }

@@ -4145,7 +4145,7 @@ int xhci_disable_slot(struct xhci_hcd *xhci, u32 slot_id) slot_id); if (ret) { spin_unlock_irqrestore(&xhci->lock, flags); - kfree(command); + xhci_free_command(xhci, command); return ret; } xhci_ring_cmd_db(xhci);