DEBIAN-CVE-2022-49605

In the Linux kernel, the following vulnerability has been resolved: igc: Reinstate IGCREMOVED logic and implement it properly The initially merged version of the igc driver code (via commit 146740f9abc4, "igc: Add support for PF") contained the following IGCREMOVED checks in the igcrd32/wr32() MMIO accessors: u32 igcrd32(struct igchw *hw, u32 reg) { u8 _iomem hw_addr = READ_ONCE(hw->hw_addr); u32 value = 0; if (IGC_REMOVED(hw_addr)) return ~value; value = readl(&hw_addr[reg]); / reads should not return all F's / if (!(~value) && (!reg || !(~readl(hw_addr)))) hw->hw_addr = NULL; return value; } And: #define wr32(reg, val) \ do { \ u8 __iomem *hw_addr = READ_ONCE((hw)->hw_addr); \ if (!IGC_REMOVED(hw_addr)) \ writel((val), &hw_addr[(reg)]); \ } while (0) E.g. igb has similar checks in its MMIO accessors, and has a similar macro E1000_REMOVED, which is implemented as follows: #define E1000_REMOVED(h) unlikely(!(h)) These checks serve to detect and take note of an 0xffffffff MMIO read return from the device, which can be caused by a PCIe link flap or some other kind of PCI bus error, and to avoid performing MMIO reads and writes from that point onwards. However, the IGC_REMOVED macro was not originally implemented: #ifndef IGC_REMOVED #define IGC_REMOVED(a) (0) #endif / IGCREMOVED */ This led to the IGCREMOVED logic to be removed entirely in a subsequent commit (commit 3c215fb18e70, "igc: remove IGCREMOVED function"), with the rationale that such checks matter only for virtualization and that igc does not support virtualization -- but a PCIe device can become detached even without virtualization being in use, and without proper checks, a PCIe bus error affecting an igc adapter will lead to various NULL pointer dereferences, as the first access after the error will set hw->hwaddr to NULL, and subsequent accesses will blindly dereference this now-NULL pointer. This patch reinstates the IGCREMOVED checks in igcrd32/wr32(), and implements IGCREMOVED the way it is done for igb, by checking for the unlikely() case of hwaddr being NULL. This change prevents the oopses seen when a PCIe link flap occurs on an igc adapter.