| Message ID | 20210725162954.9861-1-len.baker@gmx.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drivers/edac/edac_mc: Remove all strcpy() uses | expand |
On 25.07.21 18:29:54, Len Baker wrote: > strcpy() performs no bounds checking on the destination buffer. This > could result in linear overflows beyond the end of the buffer, leading > to all kinds of misbehaviors. The safe replacement is strscpy(). > > However, to add labels is better to use the scnprintf to simplify the > arithmetic. > > This is a previous step in the path to remove the strcpy() function > entirely from the kernel. > > Signed-off-by: Len Baker <len.baker@gmx.com> > --- > This is a task of the KSPP [1] > > [1] https://github.com/KSPP/linux/issues/88 > > drivers/edac/edac_mc.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c > index f6d462d0be2d..1286364f0e48 100644 > --- a/drivers/edac/edac_mc.c > +++ b/drivers/edac/edac_mc.c > @@ -1027,6 +1027,7 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type, > { > struct dimm_info *dimm; > char *p; > + size_t p_size = 0; I would rather use a 'left' variable which is initialized with sizeof(e->label) close to there p = e->label is. > int row = -1, chan = -1; > int pos[EDAC_MAX_LAYERS] = { top_layer, mid_layer, low_layer }; > int i, n_labels = 0; > @@ -1113,12 +1114,11 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type, > p = e->label; > *p = '\0'; > } else { > - if (p != e->label) { > - strcpy(p, OTHER_LABEL); > - p += strlen(OTHER_LABEL); > - } > - strcpy(p, dimm->label); > - p += strlen(p); > + const char *or = (p != e->label) ? OTHER_LABEL : ""; > + > + p_size += scnprintf(p + p_size, > + sizeof(e->label) - p_size, > + "%s%s", or, dimm->label); My preference is to advance p here (and decrement 'left'). This is the pattern how p is used throughout the code. I also don't see a benefit of using scnprintf() here compared to the previous implementation. Thanks, -Robert > } > > /* > @@ -1140,9 +1140,9 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type, > } > > if (any_memory) > - strcpy(e->label, "any memory"); > + strscpy(e->label, "any memory", sizeof(e->label)); > else if (!*e->label) > - strcpy(e->label, "unknown memory"); > + strscpy(e->label, "unknown memory", sizeof(e->label)); > > edac_inc_csrow(e, row, chan); > > -- > 2.25.1 >
Hi, On Tue, Jul 27, 2021 at 02:38:47PM +0200, Robert Richter wrote: > On 25.07.21 18:29:54, Len Baker wrote: > > drivers/edac/edac_mc.c | 16 ++++++++-------- > > 1 file changed, 8 insertions(+), 8 deletions(-) > > > > diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c > > index f6d462d0be2d..1286364f0e48 100644 > > --- a/drivers/edac/edac_mc.c > > +++ b/drivers/edac/edac_mc.c > > @@ -1027,6 +1027,7 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type, > > { > > struct dimm_info *dimm; > > char *p; > > + size_t p_size = 0; > > I would rather use a 'left' variable which is initialized with > sizeof(e->label) close to there p = e->label is. Ok. > > int row = -1, chan = -1; > > int pos[EDAC_MAX_LAYERS] = { top_layer, mid_layer, low_layer }; > > int i, n_labels = 0; > > @@ -1113,12 +1114,11 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type, > > p = e->label; > > *p = '\0'; > > } else { > > - if (p != e->label) { > > - strcpy(p, OTHER_LABEL); > > - p += strlen(OTHER_LABEL); > > - } > > - strcpy(p, dimm->label); > > - p += strlen(p); > > + const char *or = (p != e->label) ? OTHER_LABEL : ""; > > + > > + p_size += scnprintf(p + p_size, > > + sizeof(e->label) - p_size, > > + "%s%s", or, dimm->label); > > My preference is to advance p here (and decrement 'left'). This is the > pattern how p is used throughout the code. I also don't see a benefit > of using scnprintf() here compared to the previous implementation. Ok, no problem. I will send a new version more close to the original. The scnprintf() returns the number of bytes writes to the buffer, so it is not necessary to use the strlen() function. But if you prefer the current pattern I will have no objection. Regards, Len
diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c index f6d462d0be2d..1286364f0e48 100644 --- a/drivers/edac/edac_mc.c +++ b/drivers/edac/edac_mc.c @@ -1027,6 +1027,7 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type, { struct dimm_info *dimm; char *p; + size_t p_size = 0; int row = -1, chan = -1; int pos[EDAC_MAX_LAYERS] = { top_layer, mid_layer, low_layer }; int i, n_labels = 0; @@ -1113,12 +1114,11 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type, p = e->label; *p = '\0'; } else { - if (p != e->label) { - strcpy(p, OTHER_LABEL); - p += strlen(OTHER_LABEL); - } - strcpy(p, dimm->label); - p += strlen(p); + const char *or = (p != e->label) ? OTHER_LABEL : ""; + + p_size += scnprintf(p + p_size, + sizeof(e->label) - p_size, + "%s%s", or, dimm->label); } /* @@ -1140,9 +1140,9 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type, } if (any_memory) - strcpy(e->label, "any memory"); + strscpy(e->label, "any memory", sizeof(e->label)); else if (!*e->label) - strcpy(e->label, "unknown memory"); + strscpy(e->label, "unknown memory", sizeof(e->label)); edac_inc_csrow(e, row, chan);
strcpy() performs no bounds checking on the destination buffer. This could result in linear overflows beyond the end of the buffer, leading to all kinds of misbehaviors. The safe replacement is strscpy(). However, to add labels is better to use the scnprintf to simplify the arithmetic. This is a previous step in the path to remove the strcpy() function entirely from the kernel. Signed-off-by: Len Baker <len.baker@gmx.com> --- This is a task of the KSPP [1] [1] https://github.com/KSPP/linux/issues/88 drivers/edac/edac_mc.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) -- 2.25.1