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-rw-r--r--fs/readdir.c79
1 files changed, 40 insertions, 39 deletions
diff --git a/fs/readdir.c b/fs/readdir.c
index d26d5ea4de7b..de2eceffdee8 100644
--- a/fs/readdir.c
+++ b/fs/readdir.c
@@ -102,10 +102,14 @@ EXPORT_SYMBOL(iterate_dir);
* filename length, and the above "soft error" worry means
* that it's probably better left alone until we have that
* issue clarified.
+ *
+ * Note the PATH_MAX check - it's arbitrary but the real
+ * kernel limit on a possible path component, not NAME_MAX,
+ * which is the technical standard limit.
*/
static int verify_dirent_name(const char *name, int len)
{
- if (!len)
+ if (len <= 0 || len >= PATH_MAX)
return -EIO;
if (memchr(name, '/', len))
return -EIO;
@@ -206,7 +210,7 @@ struct linux_dirent {
struct getdents_callback {
struct dir_context ctx;
struct linux_dirent __user * current_dir;
- struct linux_dirent __user * previous;
+ int prev_reclen;
int count;
int error;
};
@@ -214,12 +218,13 @@ struct getdents_callback {
static int filldir(struct dir_context *ctx, const char *name, int namlen,
loff_t offset, u64 ino, unsigned int d_type)
{
- struct linux_dirent __user * dirent;
+ struct linux_dirent __user *dirent, *prev;
struct getdents_callback *buf =
container_of(ctx, struct getdents_callback, ctx);
unsigned long d_ino;
int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
sizeof(long));
+ int prev_reclen;
buf->error = verify_dirent_name(name, namlen);
if (unlikely(buf->error))
@@ -232,28 +237,24 @@ static int filldir(struct dir_context *ctx, const char *name, int namlen,
buf->error = -EOVERFLOW;
return -EOVERFLOW;
}
- dirent = buf->previous;
- if (dirent && signal_pending(current))
+ prev_reclen = buf->prev_reclen;
+ if (prev_reclen && signal_pending(current))
return -EINTR;
-
- /*
- * Note! This range-checks 'previous' (which may be NULL).
- * The real range was checked in getdents
- */
- if (!user_access_begin(dirent, sizeof(*dirent)))
- goto efault;
- if (dirent)
- unsafe_put_user(offset, &dirent->d_off, efault_end);
dirent = buf->current_dir;
+ prev = (void __user *) dirent - prev_reclen;
+ if (!user_access_begin(prev, reclen + prev_reclen))
+ goto efault;
+
+ /* This might be 'dirent->d_off', but if so it will get overwritten */
+ unsafe_put_user(offset, &prev->d_off, efault_end);
unsafe_put_user(d_ino, &dirent->d_ino, efault_end);
unsafe_put_user(reclen, &dirent->d_reclen, efault_end);
unsafe_put_user(d_type, (char __user *) dirent + reclen - 1, efault_end);
unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end);
user_access_end();
- buf->previous = dirent;
- dirent = (void __user *)dirent + reclen;
- buf->current_dir = dirent;
+ buf->current_dir = (void __user *)dirent + reclen;
+ buf->prev_reclen = reclen;
buf->count -= reclen;
return 0;
efault_end:
@@ -267,7 +268,6 @@ SYSCALL_DEFINE3(getdents, unsigned int, fd,
struct linux_dirent __user *, dirent, unsigned int, count)
{
struct fd f;
- struct linux_dirent __user * lastdirent;
struct getdents_callback buf = {
.ctx.actor = filldir,
.count = count,
@@ -285,8 +285,10 @@ SYSCALL_DEFINE3(getdents, unsigned int, fd,
error = iterate_dir(f.file, &buf.ctx);
if (error >= 0)
error = buf.error;
- lastdirent = buf.previous;
- if (lastdirent) {
+ if (buf.prev_reclen) {
+ struct linux_dirent __user * lastdirent;
+ lastdirent = (void __user *)buf.current_dir - buf.prev_reclen;
+
if (put_user(buf.ctx.pos, &lastdirent->d_off))
error = -EFAULT;
else
@@ -299,7 +301,7 @@ SYSCALL_DEFINE3(getdents, unsigned int, fd,
struct getdents_callback64 {
struct dir_context ctx;
struct linux_dirent64 __user * current_dir;
- struct linux_dirent64 __user * previous;
+ int prev_reclen;
int count;
int error;
};
@@ -307,11 +309,12 @@ struct getdents_callback64 {
static int filldir64(struct dir_context *ctx, const char *name, int namlen,
loff_t offset, u64 ino, unsigned int d_type)
{
- struct linux_dirent64 __user *dirent;
+ struct linux_dirent64 __user *dirent, *prev;
struct getdents_callback64 *buf =
container_of(ctx, struct getdents_callback64, ctx);
int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1,
sizeof(u64));
+ int prev_reclen;
buf->error = verify_dirent_name(name, namlen);
if (unlikely(buf->error))
@@ -319,30 +322,27 @@ static int filldir64(struct dir_context *ctx, const char *name, int namlen,
buf->error = -EINVAL; /* only used if we fail.. */
if (reclen > buf->count)
return -EINVAL;
- dirent = buf->previous;
- if (dirent && signal_pending(current))
+ prev_reclen = buf->prev_reclen;
+ if (prev_reclen && signal_pending(current))
return -EINTR;
-
- /*
- * Note! This range-checks 'previous' (which may be NULL).
- * The real range was checked in getdents
- */
- if (!user_access_begin(dirent, sizeof(*dirent)))
- goto efault;
- if (dirent)
- unsafe_put_user(offset, &dirent->d_off, efault_end);
dirent = buf->current_dir;
+ prev = (void __user *)dirent - prev_reclen;
+ if (!user_access_begin(prev, reclen + prev_reclen))
+ goto efault;
+
+ /* This might be 'dirent->d_off', but if so it will get overwritten */
+ unsafe_put_user(offset, &prev->d_off, efault_end);
unsafe_put_user(ino, &dirent->d_ino, efault_end);
unsafe_put_user(reclen, &dirent->d_reclen, efault_end);
unsafe_put_user(d_type, &dirent->d_type, efault_end);
unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end);
user_access_end();
- buf->previous = dirent;
- dirent = (void __user *)dirent + reclen;
- buf->current_dir = dirent;
+ buf->prev_reclen = reclen;
+ buf->current_dir = (void __user *)dirent + reclen;
buf->count -= reclen;
return 0;
+
efault_end:
user_access_end();
efault:
@@ -354,7 +354,6 @@ int ksys_getdents64(unsigned int fd, struct linux_dirent64 __user *dirent,
unsigned int count)
{
struct fd f;
- struct linux_dirent64 __user * lastdirent;
struct getdents_callback64 buf = {
.ctx.actor = filldir64,
.count = count,
@@ -372,9 +371,11 @@ int ksys_getdents64(unsigned int fd, struct linux_dirent64 __user *dirent,
error = iterate_dir(f.file, &buf.ctx);
if (error >= 0)
error = buf.error;
- lastdirent = buf.previous;
- if (lastdirent) {
+ if (buf.prev_reclen) {
+ struct linux_dirent64 __user * lastdirent;
typeof(lastdirent->d_off) d_off = buf.ctx.pos;
+
+ lastdirent = (void __user *) buf.current_dir - buf.prev_reclen;
if (__put_user(d_off, &lastdirent->d_off))
error = -EFAULT;
else
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-03 14:29:54 +0000