| Message ID | 20250416020109.work.297-kees@kernel.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | net/mlx5e: ethtool: Fix formatting of ptp_rq0_csum_complete_tail_slow | expand |
On Tue, Apr 15, 2025 at 07:01:14PM -0700, Kees Cook wrote: > The new GCC 15 warning -Wunterminated-string-initialization reports: > > In file included from drivers/net/ethernet/mellanox/mlx5/core/en.h:55, > from drivers/net/ethernet/mellanox/mlx5/core/en_stats.c:34: > drivers/net/ethernet/mellanox/mlx5/core/en_stats.h:57:46: warning: initializer-string for array of 'char' truncates NUL terminator but destination lacks 'nonstring' attribute (33 chars into 32 available) [-Wunterminated-string-initialization] > 57 | #define MLX5E_DECLARE_PTP_RQ_STAT(type, fld) "ptp_rq%d_"#fld, offsetof(type, fld) > | ^~~~~~~~~~~ > drivers/net/ethernet/mellanox/mlx5/core/en_stats.c:2279:11: note: in expansion of macro 'MLX5E_DECLARE_PTP_RQ_STAT' > 2279 | { MLX5E_DECLARE_PTP_RQ_STAT(struct mlx5e_rq_stats, csum_complete_tail_slow) }, > | ^~~~~~~~~~~~~~~~~~~~~~~~~ > > This stat string is being used in ethtool_sprintf(), so it must be a > valid NUL-terminated string. Currently the string lacks the final NUL > byte (as GCC warns), but by absolute luck, the next byte in memory is a > space (decimal 32) followed by a NUL. "format" is immediately followed > by little-endian size_t: > > struct counter_desc { > char format[32]; /* 0 32 */ > size_t offset; /* 32 8 */ > }; > > The "offset" member is populated by the stats member offset: > > #define MLX5E_DECLARE_PTP_RQ_STAT(type, fld) "ptp_rq%d_"#fld, offsetof(type, fld) > > which for this struct mlx5e_rq_stats member, csum_complete_tail_slow, is > 32, or space, and then the rest of the "offset" bytes are NULs. > > struct mlx5e_rq_stats { > ... > u64 csum_complete_tail_slow; /* 32 8 */ > > The use of vsnprintf(), within ethtool_sprintf(), reads past the end of > "format" and sees the format string as "ptp_rq%d_csum_complete_tail_slow ", > with %d getting resolved by MLX5E_PTP_CHANNEL_IX (value 0): > > ethtool_sprintf(data, ptp_rq_stats_desc[i].format, > MLX5E_PTP_CHANNEL_IX); > > With an output result of "ptp_rq0_csum_complete_tail_slow", which gets > precisely truncated to 31 characters with a trailing NUL. > > So, instead of accidentally getting this correct due to the NUL bytes > at the end of the size_t that happens to follow the format string, just > make the string initializer 1 byte shorter by replacing "%d" with "0", > since MLX5E_PTP_CHANNEL_IX is already hard-coded. This results in no > initializer truncation and no need to call sprintf(). > Thanks for the detailed write-up! > Signed-off-by: Kees Cook <kees@kernel.org> > --- > Cc: Saeed Mahameed <saeedm@nvidia.com> > Cc: Tariq Toukan <tariqt@nvidia.com> > Cc: Leon Romanovsky <leon@kernel.org> > Cc: Andrew Lunn <andrew+netdev@lunn.ch> > Cc: "David S. Miller" <davem@davemloft.net> > Cc: Eric Dumazet <edumazet@google.com> > Cc: Jakub Kicinski <kuba@kernel.org> > Cc: Paolo Abeni <pabeni@redhat.com> > Cc: Richard Cochran <richardcochran@gmail.com> > Cc: netdev@vger.kernel.org > Cc: linux-rdma@vger.kernel.org > --- > drivers/net/ethernet/mellanox/mlx5/core/en_stats.c | 3 +-- > drivers/net/ethernet/mellanox/mlx5/core/en_stats.h | 2 +- > 2 files changed, 2 insertions(+), 3 deletions(-) > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c > index 1c121b435016..19664fa7f217 100644 > --- a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c > +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c > @@ -2424,8 +2424,7 @@ static MLX5E_DECLARE_STATS_GRP_OP_FILL_STRS(ptp) > } > if (priv->rx_ptp_opened) { > for (i = 0; i < NUM_PTP_RQ_STATS; i++) > - ethtool_sprintf(data, ptp_rq_stats_desc[i].format, > - MLX5E_PTP_CHANNEL_IX); > + ethtool_puts(data, ptp_rq_stats_desc[i].format); > } > } > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h > index 8de6fcbd3a03..def5dea1463d 100644 > --- a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h > +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h > @@ -54,7 +54,7 @@ > #define MLX5E_DECLARE_PTP_TX_STAT(type, fld) "ptp_tx%d_"#fld, offsetof(type, fld) > #define MLX5E_DECLARE_PTP_CH_STAT(type, fld) "ptp_ch_"#fld, offsetof(type, fld) > #define MLX5E_DECLARE_PTP_CQ_STAT(type, fld) "ptp_cq%d_"#fld, offsetof(type, fld) > -#define MLX5E_DECLARE_PTP_RQ_STAT(type, fld) "ptp_rq%d_"#fld, offsetof(type, fld) > +#define MLX5E_DECLARE_PTP_RQ_STAT(type, fld) "ptp_rq0_"#fld, offsetof(type, fld) > > #define MLX5E_DECLARE_QOS_TX_STAT(type, fld) "qos_tx%d_"#fld, offsetof(type, fld) > > -- > 2.34.1 > > Thought of renaming the stat but then it will impact current users which is worse: csum_complete_tail_slow is a regular rq stat as well. So: Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com> Thanks, Dragos
Hello: This patch was applied to netdev/net-next.git (main) by Jakub Kicinski <kuba@kernel.org>: On Tue, 15 Apr 2025 19:01:14 -0700 you wrote: > The new GCC 15 warning -Wunterminated-string-initialization reports: > > In file included from drivers/net/ethernet/mellanox/mlx5/core/en.h:55, > from drivers/net/ethernet/mellanox/mlx5/core/en_stats.c:34: > drivers/net/ethernet/mellanox/mlx5/core/en_stats.h:57:46: warning: initializer-string for array of 'char' truncates NUL terminator but destination lacks 'nonstring' attribute (33 chars into 32 available) [-Wunterminated-string-initialization] > 57 | #define MLX5E_DECLARE_PTP_RQ_STAT(type, fld) "ptp_rq%d_"#fld, offsetof(type, fld) > | ^~~~~~~~~~~ > drivers/net/ethernet/mellanox/mlx5/core/en_stats.c:2279:11: note: in expansion of macro 'MLX5E_DECLARE_PTP_RQ_STAT' > 2279 | { MLX5E_DECLARE_PTP_RQ_STAT(struct mlx5e_rq_stats, csum_complete_tail_slow) }, > | ^~~~~~~~~~~~~~~~~~~~~~~~~ > > [...] Here is the summary with links: - net/mlx5e: ethtool: Fix formatting of ptp_rq0_csum_complete_tail_slow https://git.kernel.org/netdev/net-next/c/cfba1d1b61ae You are awesome, thank you!
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c index 1c121b435016..19664fa7f217 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c @@ -2424,8 +2424,7 @@ static MLX5E_DECLARE_STATS_GRP_OP_FILL_STRS(ptp) } if (priv->rx_ptp_opened) { for (i = 0; i < NUM_PTP_RQ_STATS; i++) - ethtool_sprintf(data, ptp_rq_stats_desc[i].format, - MLX5E_PTP_CHANNEL_IX); + ethtool_puts(data, ptp_rq_stats_desc[i].format); } } diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h index 8de6fcbd3a03..def5dea1463d 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h @@ -54,7 +54,7 @@ #define MLX5E_DECLARE_PTP_TX_STAT(type, fld) "ptp_tx%d_"#fld, offsetof(type, fld) #define MLX5E_DECLARE_PTP_CH_STAT(type, fld) "ptp_ch_"#fld, offsetof(type, fld) #define MLX5E_DECLARE_PTP_CQ_STAT(type, fld) "ptp_cq%d_"#fld, offsetof(type, fld) -#define MLX5E_DECLARE_PTP_RQ_STAT(type, fld) "ptp_rq%d_"#fld, offsetof(type, fld) +#define MLX5E_DECLARE_PTP_RQ_STAT(type, fld) "ptp_rq0_"#fld, offsetof(type, fld) #define MLX5E_DECLARE_QOS_TX_STAT(type, fld) "qos_tx%d_"#fld, offsetof(type, fld)
The new GCC 15 warning -Wunterminated-string-initialization reports: In file included from drivers/net/ethernet/mellanox/mlx5/core/en.h:55, from drivers/net/ethernet/mellanox/mlx5/core/en_stats.c:34: drivers/net/ethernet/mellanox/mlx5/core/en_stats.h:57:46: warning: initializer-string for array of 'char' truncates NUL terminator but destination lacks 'nonstring' attribute (33 chars into 32 available) [-Wunterminated-string-initialization] 57 | #define MLX5E_DECLARE_PTP_RQ_STAT(type, fld) "ptp_rq%d_"#fld, offsetof(type, fld) | ^~~~~~~~~~~ drivers/net/ethernet/mellanox/mlx5/core/en_stats.c:2279:11: note: in expansion of macro 'MLX5E_DECLARE_PTP_RQ_STAT' 2279 | { MLX5E_DECLARE_PTP_RQ_STAT(struct mlx5e_rq_stats, csum_complete_tail_slow) }, | ^~~~~~~~~~~~~~~~~~~~~~~~~ This stat string is being used in ethtool_sprintf(), so it must be a valid NUL-terminated string. Currently the string lacks the final NUL byte (as GCC warns), but by absolute luck, the next byte in memory is a space (decimal 32) followed by a NUL. "format" is immediately followed by little-endian size_t: struct counter_desc { char format[32]; /* 0 32 */ size_t offset; /* 32 8 */ }; The "offset" member is populated by the stats member offset: #define MLX5E_DECLARE_PTP_RQ_STAT(type, fld) "ptp_rq%d_"#fld, offsetof(type, fld) which for this struct mlx5e_rq_stats member, csum_complete_tail_slow, is 32, or space, and then the rest of the "offset" bytes are NULs. struct mlx5e_rq_stats { ... u64 csum_complete_tail_slow; /* 32 8 */ The use of vsnprintf(), within ethtool_sprintf(), reads past the end of "format" and sees the format string as "ptp_rq%d_csum_complete_tail_slow ", with %d getting resolved by MLX5E_PTP_CHANNEL_IX (value 0): ethtool_sprintf(data, ptp_rq_stats_desc[i].format, MLX5E_PTP_CHANNEL_IX); With an output result of "ptp_rq0_csum_complete_tail_slow", which gets precisely truncated to 31 characters with a trailing NUL. So, instead of accidentally getting this correct due to the NUL bytes at the end of the size_t that happens to follow the format string, just make the string initializer 1 byte shorter by replacing "%d" with "0", since MLX5E_PTP_CHANNEL_IX is already hard-coded. This results in no initializer truncation and no need to call sprintf(). Signed-off-by: Kees Cook <kees@kernel.org> --- Cc: Saeed Mahameed <saeedm@nvidia.com> Cc: Tariq Toukan <tariqt@nvidia.com> Cc: Leon Romanovsky <leon@kernel.org> Cc: Andrew Lunn <andrew+netdev@lunn.ch> Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Paolo Abeni <pabeni@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: netdev@vger.kernel.org Cc: linux-rdma@vger.kernel.org --- drivers/net/ethernet/mellanox/mlx5/core/en_stats.c | 3 +-- drivers/net/ethernet/mellanox/mlx5/core/en_stats.h | 2 +- 2 files changed, 2 insertions(+), 3 deletions(-)