| Message ID | YT8S3poKyd5Nr5cK@rric.localdomain (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | EDAC/mc: Prefer strscpy or scnprintf over strcpy, sprintf and snprintf | expand |
On Mon, Sep 13, 2021 at 10:59:10AM +0200, Robert Richter wrote: > From 01a3c62a533e71984dfff7189e247b3e848f1449 Mon Sep 17 00:00:00 2001 > From: Len Baker <len.baker@gmx.com> > Date: Fri, 3 Sep 2021 17:05:39 +0200 > Subject: [PATCH] EDAC/mc: Prefer strscpy or scnprintf over strcpy, sprintf > and snprintf > > 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(). > [1][2] > > However, to simplify and clarify the code, to concatenate labels use > the scnprintf() function. This way it is not necessary to check the > return value of strscpy (-E2BIG if the parameter count is 0 or the src > was truncated) since the scnprintf returns always the number of chars > written into the buffer. This function returns always a nul-terminated > string even if it needs to be truncated. > > While at it, fix all other broken string generation code that wrongly > interprets snprintf()'s return code or just uses sprintf(), implement > that using scnprintf() here too. Drop breaks in loops around > scnprintf() as it is safe now to loop. Moreover, the check is > needless: For the case when the buffer is exhausted, len never gets > zero because scnprintf() takes the full buffer length as input > parameter, but excludes the trailing '\0' in its return code and thus, > 1 is the minimum len. > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy > [2] https://github.com/KSPP/linux/issues/88 > > [ rric: Replace snprintf() with scnprintf(), rework sprintf() user, > drop breaks in loops around scnprintf(), introduce 'end' pointer to > reduce pointer arithmetic, use prefix pattern for e->location, > adjust subject and description ] > > Co-developed-by: Joe Perches <joe@perches.com> > Signed-off-by: Joe Perches <joe@perches.com> > Signed-off-by: Len Baker <len.baker@gmx.com> > Signed-off-by: Robert Richter <rrichter@amd.com> > --- > drivers/edac/edac_mc.c | 42 ++++++++++++++++++------------------------ > 1 file changed, 18 insertions(+), 24 deletions(-) Applied, thanks.
Hi, On Mon, Sep 13, 2021 at 10:59:10AM +0200, Robert Richter wrote: > this patch looks good to me. I made some changes on top of it to > further ease pointer arithmetic and also fix remaining > sprintf/snprintf() users as it makes sense to have them all in a > single change. See below. Boris, please apply. Thanks Robert for doing this. Regards, Len
diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c index 2c5975674723..9f82ca295353 100644 --- a/drivers/edac/edac_mc.c +++ b/drivers/edac/edac_mc.c @@ -66,14 +66,12 @@ unsigned int edac_dimm_info_location(struct dimm_info *dimm, char *buf, char *p = buf; for (i = 0; i < mci->n_layers; i++) { - n = snprintf(p, len, "%s %d ", + n = scnprintf(p, len, "%s %d ", edac_layer_name[mci->layers[i].type], dimm->location[i]); p += n; len -= n; count += n; - if (!len) - break; } return count; @@ -341,19 +339,16 @@ static int edac_mc_alloc_dimms(struct mem_ctl_info *mci) */ len = sizeof(dimm->label); p = dimm->label; - n = snprintf(p, len, "mc#%u", mci->mc_idx); + n = scnprintf(p, len, "mc#%u", mci->mc_idx); p += n; len -= n; for (layer = 0; layer < mci->n_layers; layer++) { - n = snprintf(p, len, "%s#%u", - edac_layer_name[mci->layers[layer].type], - pos[layer]); + n = scnprintf(p, len, "%s#%u", + edac_layer_name[mci->layers[layer].type], + pos[layer]); p += n; len -= n; dimm->location[layer] = pos[layer]; - - if (len <= 0) - break; } /* Link it to the csrows old API data */ @@ -1027,12 +1022,13 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type, const char *other_detail) { struct dimm_info *dimm; - char *p; + char *p, *end; int row = -1, chan = -1; int pos[EDAC_MAX_LAYERS] = { top_layer, mid_layer, low_layer }; int i, n_labels = 0; struct edac_raw_error_desc *e = &mci->error_desc; bool any_memory = true; + const char *prefix; edac_dbg(3, "MC%d\n", mci->mc_idx); @@ -1087,6 +1083,8 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type, */ p = e->label; *p = '\0'; + end = p + sizeof(e->label); + prefix = ""; mci_for_each_dimm(mci, dimm) { if (top_layer >= 0 && top_layer != dimm->location[0]) @@ -1114,12 +1112,8 @@ 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); + p += scnprintf(p, end - p, "%s%s", prefix, dimm->label); + prefix = OTHER_LABEL; } /* @@ -1141,25 +1135,25 @@ 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); /* Fill the RAM location data */ p = e->location; + end = p + sizeof(e->location); + prefix = ""; for (i = 0; i < mci->n_layers; i++) { if (pos[i] < 0) continue; - p += sprintf(p, "%s:%d ", - edac_layer_name[mci->layers[i].type], - pos[i]); + p += scnprintf(p, end - p, "%s%s:%d", prefix, + edac_layer_name[mci->layers[i].type], pos[i]); + prefix = " "; } - if (p > e->location) - *(p - 1) = '\0'; edac_raw_mc_handle_error(e); }