diff options
| author | Vitaly Chikunov <vt@altlinux.org> | 2022-02-16 21:18:21 +0300 |
|---|---|---|
| committer | Christian Schoenebeck <qemu_oss@crudebyte.com> | 2022-02-17 16:57:58 +0100 |
| commit | e64e27d5cb103b7764f1a05b6eda7e7fedd517c5 (patch) | |
| tree | 6f349f7536e1b2e9ee569f7363b9802e82fb8e20 /util | |
| parent | 494fbbd3ed46a14ef0924651c058b9b0dcb4a7b4 (diff) | |
9pfs: Fix segfault in do_readdir_many caused by struct dirent overread
`struct dirent' returned from readdir(3) could be shorter (or longer)
than `sizeof(struct dirent)', thus memcpy of sizeof length will overread
into unallocated page causing SIGSEGV. Example stack trace:
#0 0x00005555559ebeed v9fs_co_readdir_many (/usr/bin/qemu-system-x86_64 + 0x497eed)
#1 0x00005555559ec2e9 v9fs_readdir (/usr/bin/qemu-system-x86_64 + 0x4982e9)
#2 0x0000555555eb7983 coroutine_trampoline (/usr/bin/qemu-system-x86_64 + 0x963983)
#3 0x00007ffff73e0be0 n/a (n/a + 0x0)
While fixing this, provide a helper for any future `struct dirent' cloning.
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/841
Cc: qemu-stable@nongnu.org
Co-authored-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Vitaly Chikunov <vt@altlinux.org>
Tested-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Acked-by: Greg Kurz <groug@kaod.org>
Tested-by: Vitaly Chikunov <vt@altlinux.org>
Message-Id: <20220216181821.3481527-1-vt@altlinux.org>
[C.S. - Fix typo in source comment. ]
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Diffstat (limited to 'util')
| -rw-r--r-- | util/osdep.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/util/osdep.c b/util/osdep.c index 42a0a4986a..67fbf22778 100644 --- a/util/osdep.c +++ b/util/osdep.c @@ -33,6 +33,7 @@ extern int madvise(char *, size_t, int); #endif +#include <dirent.h> #include "qemu-common.h" #include "qemu/cutils.h" #include "qemu/sockets.h" @@ -615,3 +616,23 @@ writev(int fd, const struct iovec *iov, int iov_cnt) return readv_writev(fd, iov, iov_cnt, true); } #endif + +struct dirent * +qemu_dirent_dup(struct dirent *dent) +{ + size_t sz = 0; +#if defined _DIRENT_HAVE_D_RECLEN + /* Avoid use of strlen() if platform supports d_reclen. */ + sz = dent->d_reclen; +#endif + /* + * Test sz for zero even if d_reclen is available + * because some drivers may set d_reclen to zero. + */ + if (sz == 0) { + /* Fallback to the most portable way. */ + sz = offsetof(struct dirent, d_name) + + strlen(dent->d_name) + 1; + } + return g_memdup(dent, sz); +} |