CVE-2025-38439

In the Linux kernel, the following vulnerability has been resolved:

bnxt_en: Set DMA unmap len correctly for XDP_REDIRECT

When transmitting an XDP_REDIRECT packet, call dma_unmap_len_set() with the proper length instead of 0. This bug triggers this warning on a system with IOMMU enabled:

WARNING: CPU: 36 PID: 0 at drivers/iommu/dma-iommu.c:842 __iommu_dma_unmap+0x159/0x170 RIP: 0010:__iommu_dma_unmap+0x159/0x170 Code: a8 00 00 00 00 48 c7 45 b0 00 00 00 00 48 c7 45 c8 00 00 00 00 48 c7 45 a0 ff ff ff ff 4c 89 45 b8 4c 89 45 c0 e9 77 ff ff ff <0f> 0b e9 60 ff ff ff e8 8b bf 6a 00 66 66 2e 0f 1f 84 00 00 00 00 RSP: 0018:ff22d31181150c88 EFLAGS: 00010206 RAX: 0000000000002000 RBX: 00000000e13a0000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ff22d31181150cf0 R08: ff22d31181150ca8 R09: 0000000000000000 R10: 0000000000000000 R11: ff22d311d36c9d80 R12: 0000000000001000 R13: ff13544d10645010 R14: ff22d31181150c90 R15: ff13544d0b2bac00 FS: 0000000000000000(0000) GS:ff13550908a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005be909dacff8 CR3: 0008000173408003 CR4: 0000000000f71ef0 PKRU: 55555554 Call Trace: <IRQ> ? show_regs+0x6d/0x80 ? __warn+0x89/0x160 ? __iommu_dma_unmap+0x159/0x170 ? report_bug+0x17e/0x1b0 ? handle_bug+0x46/0x90 ? exc_invalid_op+0x18/0x80 ? asm_exc_invalid_op+0x1b/0x20 ? __iommu_dma_unmap+0x159/0x170 ? __iommu_dma_unmap+0xb3/0x170 iommu_dma_unmap_page+0x4f/0x100 dma_unmap_page_attrs+0x52/0x220 ? srso_alias_return_thunk+0x5/0xfbef5 ? xdp_return_frame+0x2e/0xd0 bnxt_tx_int_xdp+0xdf/0x440 [bnxt_en] __bnxt_poll_work_done+0x81/0x1e0 [bnxt_en] bnxt_poll+0xd3/0x1e0 [bnxt_en]

This patch fixes a bug in the bnxt_en driver where an incorrect DMA length of zero was passed for XDP_REDIRECT, which triggered a kernel warning on systems with IOMMU enabled. The fix ensures that the proper DMA length is set before unmapping, preventing erroneous IOMMU behavior and potential kernel crashes. This issue could lead to denial-of-service under specific configurations with active XDP and IOMMU. The vulnerability does not impact confidentiality (C:N) or integrity (I:N), as no sensitive data is exposed and no unauthorized data modification occurs. However, it does affect availability (A:L), since the kernel warning caused by an invalid DMA unmap length may lead to system instability or crashes—particularly on systems with panic_on_warn=1 or strict IOMMU enforcement. No special privileges are required to trigger this issue in the kernel context, and it occurs during normal operation of the XDP_REDIRECT path in the driver, hence privileges required are rated as none (PR:N).

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.