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perf tools: Use snprintf() for root_dir path construction

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get_kernel_version() in machine.c and dso__load_guest_kernel_sym() in
symbol.c use sprintf() to construct paths by prepending root_dir to
"/proc/version" and "/proc/kallsyms" respectively.  Both write into
PATH_MAX stack buffers, but root_dir comes from --guestmount or KVM
configuration and is not length-checked.  A root_dir at or near
PATH_MAX causes a stack buffer overflow.

Switch to snprintf() with sizeof(path) to prevent overflow.

Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Fixes: a1645ce12a ("perf: 'perf kvm' tool for monitoring guest performance from host")
Cc: Zhang Yanmin <yanmin_zhang@linux.intel.com>
Assisted-by: Claude:claude-opus-4.6
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo 2026-06-10 20:34:38 -03:00
parent d2c6069d68
commit 7b0df6f4d4
2 changed files with 2 additions and 2 deletions
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2
tools/perf/util/machine.c
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@ -1336,7 +1336,7 @@ static char *get_kernel_version(const char *root_dir)
char *name, *tmp;
const char *prefix = "Linux version ";
sprintf(version, "%s/proc/version", root_dir);
snprintf(version, sizeof(version), "%s/proc/version", root_dir);
file = fopen(version, "r");
if (!file)
return NULL;

2
tools/perf/util/symbol.c
View File

@ -2283,7 +2283,7 @@ static int dso__load_guest_kernel_sym(struct dso *dso, struct map *map)
if (!kallsyms_filename)
return -1;
} else {
sprintf(path, "%s/proc/kallsyms", machine->root_dir);
snprintf(path, sizeof(path), "%s/proc/kallsyms", machine->root_dir);
kallsyms_filename = path;
}