Messages in this thread | | | Date | Mon, 25 Jul 2022 13:09:11 +0200 | From | Robert Richter <> | Subject | Re: [PATCH v2] EDAC/ghes: Fix buffer overflow in ghes_edac_register() |
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On 25.07.22 12:45:24, Robert Richter wrote: > On 25.07.22 12:14:21, Borislav Petkov wrote: > > On Mon, Jul 25, 2022 at 11:53:06AM +0200, Robert Richter wrote: > > > The dimm->label buffer must be pre-initialized zero. This broke with: > > > > > > b9cae27728d1 EDAC/ghes: Scan the system once on driver init > > > > > > since krealloc/krealloc_array() does not zero out the new allocated > > > buffer for struct dimm_info in enumerate_dimms(). This uninitialized > > > broken struct is then copied in ghes_edac_register() to the final > > > dimm_info destination. Originally, before b9cae27728d1, the struct was > > > zero initialized with kzalloc'ed by edac_mc_alloc() and directly used. > > > Now, that a copy is created first, this copy must be also zero > > > initialized. > > > > > > IMO this is the proper fix: > > > > Maybe, but this needs fixing too: > > > > /* both strings must be non-zero */ > > if (bank && *bank && device && *device) > > > > Obviously one of those strings are zero coming from that BIOS...
I see now, what you mean here, may be change this:
snprintf(dimm->label, sizeof(dimm->label), "%s %s", (bank && *bank) ? bank : "N/A", (device && *device) ? device : "N/A");
to:
snprintf(dimm->label, sizeof(dimm->label), "%s%s%s", (bank && *bank) ? bank : "", (bank && device) ? " " : "", (device && *device) ? device : "");
It keeps the default assignment from edac_mc_alloc_dimms() but changes we label if one of bank or device is given.
-Robert
> > But the label is pre-initialized in edac_mc_alloc_dimms(): > > p = dimm->label; > n = snprintf(p, len, "mc#%u", mci->mc_idx); > > You check if the label is emtpy when copying it in > ghes_edac_register(): > > if (strlen(src->label)) > memcpy(dst->label, src->label, sizeof(src->label)); > > So if there is nothing that comes from the bios, this default label > string from edac_mc_alloc_dimms() will be used. > > If you write "N/A" to the label instead, the sysfs dimm_label values > wont be unique any longer between dimms, which might break existing > applications. > > -Robert > > > > > -- > > Regards/Gruss, > > Boris. > > > > https://people.kernel.org/tglx/notes-about-netiquette
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