From: Zijun Hu <quic_zijuhu@xxxxxxxxxxx> [ Upstream commit 31e4e12e0e9609850cefd4b2e1adf782f56337d6 ] software_node_get_reference_args() wants to get @index-th element, so the property value requires at least '(index + 1) * sizeof(*ref)' bytes but that can not be guaranteed by current OOB check, and may cause OOB for malformed property. Fix by using as OOB check '((index + 1) * sizeof(*ref) > prop->length)'. Reviewed-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> Signed-off-by: Zijun Hu <quic_zijuhu@xxxxxxxxxxx> Link: https://lore.kernel.org/r/20250414-fix_swnode-v2-1-9c9e6ae11eab@xxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- ## Final Decision **YES** This commit should be backported to stable kernel trees. **Extensive Explanation:** 1. **Critical Security Fix**: This commit fixes a clear out-of-bounds memory access vulnerability in `software_node_get_reference_args()` at line 532 in `/drivers/base/swnode.c`. The original bounds check `index capability_test capability_test.c f2fs_folio_analysis.md ipv4_multipath_analysis.md ipv6_route_allocation_rcu_analysis.md ixgbe_e610_set_phys_id_analysis.md linux lpfc_timeout_analysis.md mac80211_mlo_mbssid_analysis.md pfcp_driver_historical_analysis.md rtl_bb_delay_analysis.md rtw89_mlo_analysis.md tcp_multipath_load_balance_analysis.md test_unaligned_diff test_unaligned_diff.c type_size_check type_size_check.c veth_driver_analysis.md wifi_mlo_mbssid_tx_link_id_analysis.md sizeof(*ref) >= prop->length` has an off-by-one error that allows reading beyond allocated memory when accessing `ref_array[index]`. 2. **Vulnerability Details**: The bug allows an attacker to read kernel memory beyond the allocated property buffer. To access `ref_array[index]`, the code needs `(index + 1) capability_test capability_test.c f2fs_folio_analysis.md ipv4_multipath_analysis.md ipv6_route_allocation_rcu_analysis.md ixgbe_e610_set_phys_id_analysis.md linux lpfc_timeout_analysis.md mac80211_mlo_mbssid_analysis.md pfcp_driver_historical_analysis.md rtl_bb_delay_analysis.md rtw89_mlo_analysis.md tcp_multipath_load_balance_analysis.md test_unaligned_diff test_unaligned_diff.c type_size_check type_size_check.c veth_driver_analysis.md wifi_mlo_mbssid_tx_link_id_analysis.md sizeof(*ref)` bytes, but the original check only ensures `index capability_test capability_test.c f2fs_folio_analysis.md ipv4_multipath_analysis.md ipv6_route_allocation_rcu_analysis.md ixgbe_e610_set_phys_id_analysis.md linux lpfc_timeout_analysis.md mac80211_mlo_mbssid_analysis.md pfcp_driver_historical_analysis.md rtl_bb_delay_analysis.md rtw89_mlo_analysis.md tcp_multipath_load_balance_analysis.md test_unaligned_diff test_unaligned_diff.c type_size_check type_size_check.c veth_driver_analysis.md wifi_mlo_mbssid_tx_link_id_analysis.md sizeof(*ref)` bytes are available. This creates a window where `index capability_test capability_test.c f2fs_folio_analysis.md ipv4_multipath_analysis.md ipv6_route_allocation_rcu_analysis.md ixgbe_e610_set_phys_id_analysis.md linux lpfc_timeout_analysis.md mac80211_mlo_mbssid_analysis.md pfcp_driver_historical_analysis.md rtl_bb_delay_analysis.md rtw89_mlo_analysis.md tcp_multipath_load_balance_analysis.md test_unaligned_diff test_unaligned_diff.c type_size_check type_size_check.c veth_driver_analysis.md wifi_mlo_mbssid_tx_link_id_analysis.md sizeof(*ref) < prop->length` but `(index + 1) capability_test capability_test.c f2fs_folio_analysis.md ipv4_multipath_analysis.md ipv6_route_allocation_rcu_analysis.md ixgbe_e610_set_phys_id_analysis.md linux lpfc_timeout_analysis.md mac80211_mlo_mbssid_analysis.md pfcp_driver_historical_analysis.md rtl_bb_delay_analysis.md rtw89_mlo_analysis.md tcp_multipath_load_balance_analysis.md test_unaligned_diff test_unaligned_diff.c type_size_check type_size_check.c veth_driver_analysis.md wifi_mlo_mbssid_tx_link_id_analysis.md sizeof(*ref) > prop->length`, allowing out-of-bounds access. 3. **Security Impact**: This vulnerability can lead to: - Information disclosure through kernel memory leaks - Potential system crashes from invalid memory access - Exploitation through malformed device tree properties 4. **Perfect Backport Candidate**: - **Minimal code change**: Single line fix changing `>=` to `>` and adding `+ 1` - **No feature additions**: Pure bug fix with no new functionality - **Low regression risk**: Makes bounds checking more restrictive, safer - **Core infrastructure**: Affects fundamental device property framework used across many drivers 5. **Historical Precedent**: The provided similar commits show a clear pattern - other defensive programming fixes in the same `software_node` subsystem (commits #1, #2, and #4) were all marked as suitable for backporting. This commit follows the same pattern of fixing potential memory safety issues with minimal, targeted changes. 6. **Maintainer Review**: The commit has been reviewed by Sakari Ailus, indicating community confidence in the fix. 7. **Stable Tree Compliance**: Meets all stable tree criteria - fixes important bug, minimal risk, contained change, no architectural modifications, and addresses a security vulnerability in critical kernel infrastructure. The commit represents exactly the type of fix that stable trees are designed to accommodate: a small, well-reviewed security fix that prevents potential exploitation without introducing new risks. drivers/base/swnode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c index 5c78fa6ae7725..deda7f35a0598 100644 --- a/drivers/base/swnode.c +++ b/drivers/base/swnode.c @@ -529,7 +529,7 @@ software_node_get_reference_args(const struct fwnode_handle *fwnode, if (prop->is_inline) return -EINVAL; - if (index * sizeof(*ref) >= prop->length) + if ((index + 1) * sizeof(*ref) > prop->length) return -ENOENT; ref_array = prop->pointer; -- 2.39.5
