Janneke Nieuwenhuizen writes: Hi!
>> On Mon, May 18, 2026 at 07:21:10PM -0500, Josh Kilmer wrote: [..] >>>* fakeroot correctly forwards the successful call now that errno is 0 >>>* attr_copy_fd overwrites it's size variable with the new result (33), >>>and reads well past the allocated buffer into a segfault. (It also >>>skips over it's end pointer and reads much more than 33 bytes, but >>>that's another issue) > > Do you have a recipe, preferrably a shell script example that shows > this? > >>>This appears to have been inadvertently introduced by changes in >>>#1136815. Some of the introduced !r checks probably need to be changed >>>to r > 0 to allow positive return values to be returned unmodified. > > This makes sense, have you tried that? I'm happy to try if I can > reproduce the problem. Find a patch attached. Indeed, get/list xattrs return r >=0 upon success; so !r should be changed to r >0 even. Please find a patch attached. >>>I'd also like to note that it's *not* legal for syscalls to clear >>>errno, which may now happen if you have a pre-set errno coming into a >>>modified syscall > > Where does this happen that is not OK? It's true that my patch now > "tests" getxattr/setxattr to see if it may succeed and I thought that > was a neat solution. Haven't addressed this just yet. >>> but I've not run into any issues tied to it. > > It would be nice to fix it anyway, WDYT? I was thinking about adding a test for the previous patch but that would require `attr' to be installed (with getfattr and setfatter) and make that a new (optional) dependency. WDYT? Greetings, Janneke
>From ebf5287faf86e6462fd056659249a70ebebd6ac2 Mon Sep 17 00:00:00 2001 From: Janneke Nieuwenhuizen <[email protected]> Date: Tue, 19 May 2026 07:13:20 +0200 Subject: [PATCH] Respect r > 0 success values for get/list xattrs, #closes: 1137058. --- libfakeroot.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/libfakeroot.c b/libfakeroot.c index 4406098..4cb1ebf 100644 --- a/libfakeroot.c +++ b/libfakeroot.c @@ -1908,7 +1908,7 @@ ssize_t getxattr(const char *path, const char *name, void *value, size_t size) if (fakeroot_disabled || user_xattr_p(name)) { r = next_getxattr(path, name, value, size); if (fakeroot_disabled - || !r + || r >= 0 || (errno != EPERM && errno != EOPNOTSUPP)) return r; errno = 0; @@ -1936,7 +1936,7 @@ ssize_t lgetxattr(const char *path, const char *name, void *value, size_t size) if (fakeroot_disabled || user_xattr_p(name)) { r = next_lgetxattr(path, name, value, size); if (fakeroot_disabled - || !r + || r >= 0 || (errno != EPERM && errno != EOPNOTSUPP)) return r; errno = 0; @@ -1964,7 +1964,7 @@ ssize_t fgetxattr(int fd, const char *name, void *value, size_t size) if (fakeroot_disabled || user_xattr_p(name)) { r = next_fgetxattr(fd, name, value, size); if (fakeroot_disabled - || !r + || r >= 0 || (errno != EPERM && errno != EOPNOTSUPP)) return r; errno = 0; @@ -1991,7 +1991,7 @@ ssize_t listxattr(const char *path, char *list, size_t size) r = next_listxattr(path, list, size); if (fakeroot_disabled - || !r + || r >= 0 || (errno != EPERM && errno != EOPNOTSUPP)) return r; errno = 0; @@ -2017,7 +2017,7 @@ ssize_t llistxattr(const char *path, char *list, size_t size) r = next_llistxattr(path, list, size); if (fakeroot_disabled - || !r + || r >= 0 || (errno != EPERM && errno != EOPNOTSUPP)) return r; errno = 0; @@ -2043,7 +2043,7 @@ ssize_t flistxattr(int fd, char *list, size_t size) r = next_flistxattr(fd, list, size); if (fakeroot_disabled - || !r + || r >= 0 || (errno != EPERM && errno != EOPNOTSUPP)) return r; errno = 0; -- 2.54.0
-- Janneke Nieuwenhuizen <[email protected]> | GNU LilyPond https://LilyPond.org Freelance IT https://www.JoyOfSource.com | Avatar® https://AvatarAcademy.com
