From 5d5fbfbbacd1efb13a9bf91317d4fde859ede4b9 Mon Sep 17 00:00:00 2001 From: Daehyeon Ko <4ncienth@gmail.com> Date: Tue, 15 Sep 2026 12:51:23 +0900 Subject: [PATCH] nvmet: pci-epf: reject too-short SGL segments The host controls an SGL segment's length. A nonzero length smaller than one SGL descriptor makes nr_descs zero, so nvmet_pci_epf_get_sgl_segment() reads the type byte of sgls[-1] outside the allocated buffer. If that byte contains a segment descriptor type, the function also copies the preceding 16 bytes and returns a negative descriptor count. The read was reproduced in 3/3 KASAN boots with only the host transfer mocked by a KUnit test: BUG: KASAN: slab-out-of-bounds in nvmet_pci_epf_get_sgl_segment Read of size 1 by task kunit_try_catch Call Trace: nvmet_pci_epf_get_sgl_segment nvmet_pci_epf_short_sgl_test Kernel panic - not syncing: KASAN: panic_on_warn set ... Reject segments that cannot hold one descriptor before allocating or transferring their contents. Fixes: 0faa0fe6f90e ("nvmet: New NVMe PCI endpoint function target driver") Cc: stable@vger.kernel.org Assisted-by: LLM Reviewed-by: Christoph Hellwig Signed-off-by: Daehyeon Ko <4ncienth@gmail.com> Signed-off-by: Keith Busch --- drivers/nvme/target/pci-epf.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/nvme/target/pci-epf.c b/drivers/nvme/target/pci-epf.c index 9c28367435a5..c683450df422 100644 --- a/drivers/nvme/target/pci-epf.c +++ b/drivers/nvme/target/pci-epf.c @@ -978,6 +978,9 @@ nvmet_pci_epf_get_sgl_segment(struct nvmet_pci_epf_ctrl *ctrl, int nr_descs, ret; void *buf; + if (length < sizeof(struct nvme_sgl_desc)) + return NULL; + buf = kmalloc(length, GFP_KERNEL); if (!buf) return NULL;