Module symbol names can get overwritten by live patches or ksplice in odd corner cases, so that the pointer no longer points within the string buffer. Gracefully fallback to reading the string directly from the kernel image in these cases, to avoid possible segmentation faults reading outside the bounds of strbuf. Signed-off-by: Stephen Brennan <stephen.s.brennan@xxxxxxxxxx> --- Hi folks - I encountered a segfault on a vmcore which had a module symbol that had gotten its name overwritten by a ksplice (live patch). It seems like there's not a guarantee that module symbol names _must_ live within the same symbol buffer, and there is even logic to prevent reading too much data into strbuf in those cases. This patch simply ensures that symbol names which start outside of the strbuf which we copied, are read directly from the kernel image, rather than indexing past the bounds of strbuf. I encountered this in store_module_symbols_v2() and have tested it there, but I replicated the code to the other versions. I will try to test it out on the other variants as well, but I thought I'd share the patch now. symbols.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/symbols.c b/symbols.c index 176c950..e70dd69 100644 --- a/symbols.c +++ b/symbols.c @@ -1704,7 +1704,7 @@ store_module_symbols_v1(ulong total, int mods_installed) BZERO(buf1, BUFSIZE); - if (strbuf) + if (strbuf && (unsigned long)modsym->name - first < strbuflen) strcpy(buf1, &strbuf[(ulong)modsym->name - first]); else @@ -2080,7 +2080,7 @@ store_module_symbols_6_4(ulong total, int mods_installed) BZERO(buf1, BUFSIZE); - if (strbuf) + if (strbuf && modsym_name(syms, modsym, i) - first < strbuflen) strcpy(buf1, &strbuf[modsym_name(syms, modsym, i) - first]); else read_string(modsym_name(syms, modsym, i), buf1, BUFSIZE-1); @@ -2148,7 +2148,7 @@ store_module_symbols_6_4(ulong total, int mods_installed) BZERO(buf1, BUFSIZE); - if (strbuf) + if (strbuf && modsym_name(gpl_syms, modsym, i) - first < strbuflen) strcpy(buf1, &strbuf[modsym_name(gpl_syms, modsym, i) - first]); else read_string(modsym_name(gpl_syms, modsym, i), buf1, BUFSIZE-1); @@ -2456,7 +2456,7 @@ store_module_symbols_v2(ulong total, int mods_installed) BZERO(buf1, BUFSIZE); - if (strbuf) + if (strbuf && modsym_name(syms, modsym, i) - first < strbuflen) strcpy(buf1, &strbuf[modsym_name(syms, modsym, i) - first]); else @@ -2529,7 +2529,7 @@ store_module_symbols_v2(ulong total, int mods_installed) BZERO(buf1, BUFSIZE); - if (strbuf) + if (strbuf && modsym_name(gpl_syms, modsym, i) - first < strbuflen) strcpy(buf1, &strbuf[modsym_name(gpl_syms, modsym, i) - first]); else -- 2.39.3 -- Crash-utility mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxxxxxx https://${domain_name}/admin/lists/devel.lists.crash-utility.osci.io/ Contribution Guidelines: https://github.com/crash-utility/crash/wiki
