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authorVincent Bernat <vincent@bernat.im>2015-08-15 15:49:13 +0200
committerAl Viro <viro@zeniv.linux.org.uk>2015-08-22 21:35:02 -0400
commit999b8b88c6060adf7a9b7907740ae86ace65291e (patch)
treeb8d0860768745926227e32002bdd5c249fdd4a86 /net
parent45e38cff4fce8d6871b5fa5e734e4dc9814d6056 (diff)
downloadlinux-999b8b88c6060adf7a9b7907740ae86ace65291e.tar.gz
9p: ensure err is initialized to 0 in p9_client_read/write
Some use of those functions were providing unitialized values to those
functions. Notably, when reading 0 bytes from an empty file on a 9P
filesystem, the return code of read() was not 0.

Tested with this simple program:

    #include <assert.h>
    #include <sys/types.h>
    #include <sys/stat.h>
    #include <fcntl.h>
    #include <unistd.h>

    int main(int argc, const char **argv)
    {
        assert(argc == 2);
        char buffer[256];
        int fd = open(argv[1], O_RDONLY|O_NOCTTY);
        assert(fd >= 0);
        assert(read(fd, buffer, 0) == 0);
        return 0;
    }

Cc: stable@vger.kernel.org # v4.1
Signed-off-by: Vincent Bernat <vincent@bernat.im>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'net')
-rw-r--r--net/9p/client.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/net/9p/client.c b/net/9p/client.c
index 498454b3c06c..ea79ee9a7348 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -1541,6 +1541,7 @@ p9_client_read(struct p9_fid *fid, u64 offset, struct iov_iter *to, int *err)
 	struct p9_client *clnt = fid->clnt;
 	struct p9_req_t *req;
 	int total = 0;
+	*err = 0;
 
 	p9_debug(P9_DEBUG_9P, ">>> TREAD fid %d offset %llu %d\n",
 		   fid->fid, (unsigned long long) offset, (int)iov_iter_count(to));
@@ -1620,6 +1621,7 @@ p9_client_write(struct p9_fid *fid, u64 offset, struct iov_iter *from, int *err)
 	struct p9_client *clnt = fid->clnt;
 	struct p9_req_t *req;
 	int total = 0;
+	*err = 0;
 
 	p9_debug(P9_DEBUG_9P, ">>> TWRITE fid %d offset %llu count %zd\n",
 				fid->fid, (unsigned long long) offset,