diff mbox series

[net-next,v2,1/3] mlxsw: Warn about invalid accesses to array fields

Message ID b988fb265c2f6c1206fe12d5bfdcfa188b7672d1.1720447210.git.petrm@nvidia.com (mailing list archive)
State Accepted
Commit b45c76e5f43fa66868e874a42a29bd0288a5ddce
Delegated to: Netdev Maintainers
Headers show
Series mlxsw: Improvements | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 816 this patch: 816
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 6 of 6 maintainers
netdev/build_clang success Errors and warnings before: 821 this patch: 821
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 821 this patch: 821
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 10 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-07-09--21-00 (tests: 693)

Commit Message

Petr Machata July 8, 2024, 2:23 p.m. UTC 
A forgotten or buggy variable initialization can cause out-of-bounds access
to a register or other item array field. For an overflow, such access would
mangle adjacent parts of the register payload. For an underflow, due to all
variables being unsigned, the access would likely trample unrelated memory.
Since neither is correct, replace these accesses with accesses at the index
of 0, and warn about the issue.

Suggested-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
---

Notes:
    v2:
    - changed to WARN_ONCE() with some prints

 drivers/net/ethernet/mellanox/mlxsw/item.h | 4 ++++
 1 file changed, 4 insertions(+)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/mellanox/mlxsw/item.h b/drivers/net/ethernet/mellanox/mlxsw/item.h
index cfafbeb42586..a619a0736bd1 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/item.h
+++ b/drivers/net/ethernet/mellanox/mlxsw/item.h
@@ -218,6 +218,10 @@  __mlxsw_item_bit_array_offset(const struct mlxsw_item *item,
 	}
 
 	max_index = (item->size.bytes << 3) / item->element_size - 1;
+	if (WARN_ONCE(index > max_index,
+		      "name=%s,index=%u,max_index=%u\n", item->name, index,
+		      max_index))
+		index = 0;
 	be_index = max_index - index;
 	offset = be_index * item->element_size >> 3;
 	in_byte_index  = index % (BITS_PER_BYTE / item->element_size);