From 2530d54f1145a7bf6b634f630344ed42adf388e5 Mon Sep 17 00:00:00 2001 From: Elliott Hughes Date: Thu, 8 Feb 2018 22:41:52 -0800 Subject: Fix the pidof comm and cmdline tests. If we have a 15-byte name, we don't know whether comm actually matches or is a truncated form of a longer name that has a common prefix. For example, with "this-is-a-very-long-name-that-is-too-long", we shouldn't match "this-is-a-very-" (but the old code would). The cmdline code was also broken on Android because it used basename(3) rather than getbasename. This doesn't affect glibc because there's a workaround in portability.h to ensure that we get the non-POSIX basename(3) with glibc but then a non-glibc section that ensures everyone else gets POSIX basename(3). That should probably be removed (and maybe `basename` poisoned) to prevent similar mistakes in future. Bug: http://b/73123244 --- lib/lib.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) (limited to 'lib') diff --git a/lib/lib.c b/lib/lib.c index 7f5fbbda..e5c94791 100644 --- a/lib/lib.c +++ b/lib/lib.c @@ -1036,13 +1036,13 @@ void names_to_pid(char **names, int (*callback)(pid_t pid, char *name)) for (cur = names; *cur; cur++) { struct stat st1, st2; - char *bb = basename(*cur); - off_t len; + char *bb = getbasename(*cur); + off_t len = strlen(bb); - // fast path: only matching a filename (no path) that fits in comm - if (strncmp(comm, bb, 15)) continue; - len = strlen(bb); - if (bb==*cur && len<16) goto match; + // Fast path: only matching a filename (no path) that fits in comm. + // `len` must be 14 or less because with a full 15 bytes we don't + // know whether the name fit or was truncated. + if (len<=14 && bb==*cur && !strcmp(comm, bb)) goto match; // If we have a path to existing file only match if same inode if (bb!=*cur && !stat(*cur, &st1)) { @@ -1059,12 +1059,12 @@ void names_to_pid(char **names, int (*callback)(pid_t pid, char *name)) sprintf(cmd = libbuf+16, "/proc/%u/cmdline", u); len = sizeof(libbuf)-17; if (!(cmd = readfileat(AT_FDCWD, cmd, cmd, &len))) continue; - // readfile only guarnatees one null terminator and we need two + // readfile only guarantees one null terminator and we need two // (yes the kernel should do this for us, don't care) cmd[len] = 0; } - if (!strcmp(bb, basename(cmd))) goto match; - if (bb!=*cur && !strcmp(bb, basename(cmd+strlen(cmd)+1))) goto match; + if (!strcmp(bb, getbasename(cmd))) goto match; + if (bb!=*cur && !strcmp(bb, getbasename(cmd+strlen(cmd)+1))) goto match; continue; match: if (callback(u, *cur)) break; -- cgit v1.2.3