LDP
/
man-pages
mirror of https://github.com/mkerrisk/man-pages
0
1
Fork 0
Code Releases Activity

seccomp_unotify.2: EXAMPLE: correct the check for NUL in buffer returned by read() 

In the usual case, read(fd, buf, PATH_MAX) will return PATH_MAX
bytes that include trailing garbage after the pathname. So the
right check is to scan from the start of the buffer to see if
there's a NUL, and error if there is not.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2020-10-24 10:46:28 +02:00
parent d1774d6af8
commit 1661264841
1 changed files with 7 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
man2/seccomp_unotify.2
View File

@ -1216,7 +1216,6 @@ getTargetPathname(struct seccomp_notif *req, int notifyFd,
char *path, size_t len)
{
char procMemPath[PATH_MAX];
bool res = true;
snprintf(procMemPath, sizeof(procMemPath), "/proc/%d/mem", req\->pid);
@ -1247,18 +1246,19 @@ getTargetPathname(struct seccomp_notif *req, int notifyFd,
exit(EXIT_FAILURE);
}
if (close(procMemFd) == \-1)
errExit("close\-/proc/PID/mem");
/* We have no guarantees about what was in the memory of the target
process. We therefore treat the buffer returned by pread() as
untrusted input. The buffer should be terminated by a null byte;
if not, then we will trigger an error for the target process. */
if (path[nread \- 1] != \(aq\0\(aq)
res = false;
for (int j = 0; j < nread; j++)
if (path[j] == \(aq\0\(aq)
return true;
if (close(procMemFd) == \-1)
errExit("close\-/proc/PID/mem");
return res;
return false;
}
/* Handle notifications that arrive via the SECCOMP_RET_USER_NOTIF file