Q:

Did Salman the Persian meet Isa AS?

‘Asim b. ‘Umar b. Qatada on the authority of a trustworthy informant
  from ‘Umar b. ‘Abdu’l-‘Aziz b. Marwan said that he was told that
  Salman the Persian told the apostle that his master in ‘Ammuriya told
  him to go to a certain place in Syria where there was a man who lived
  between two thickets. Every year as he used to go from one to the
  other, the sick used to stand in his way and everyone he prayed for
  was healed. He said, ‘Ask him about this religion which you seek, for
  he can tell you of it.’ So I went on until I came to the place I had
  been told of, and I found that people had gathered there with their
  sick until he came out to them that night passing from one thicket to
  the other. The people came to him with their sick and everyone he
  prayed for was healed. They prevented me from getting to him so that I
  could not approach him until he entered the thicket he was making for,
  but I took hold of his shoulder. He asked me who I was as he turned to
  me and I said, ‘God have mercy on you, tell me about the Hanifiya, the
  religion of Abraham.’ He replied, ‘You are asking about something men
  do not inquire of today; the time has come near when a prophet will be
  sent with this religion from the people of the haram. Go to him, for
  he will bring you to it.’ Then he went into the thicket. The apostle
  said to Salman, ‘If you have told me the truth, YOU MET JESUS THE SON
  OF MARY.’ 
(Guillaume, The Life of Muhammad, p. 98)

What is the authenticity of this report? Did Salman the Persian really meet Prophet Isa AS?

A:

There is an unknown (potentially weak) narrator between Asim  and Umar and a break in the chain between Umar and Salman so its authenticity is questionable.
Ibn Kathir in البداية والنهاية comments on this tradition as follows:

هكذا وقع في هذه الرواية. وفيها رجل مبهم وهو شيخ عاصم بن عمر بن قتادة.
  وقد قيل إنه الحسن ابن عمارة ثم هو منقطع بل معضل بين عمر بن عبد العزيز
  وسلمان رضي الله عنه. قوله لئن كنت صدقتني يا سلمان لقد لقيت عيسى بن
  مريم غريب جدا بل منكر. فإن الفترة أقل ما قيل فيها أنها أربعمائة سنة،
  وقيل ستمائة سنة بالشمسية، وسلمان أكثر ما قيل أنه عاش ثلاثمائة سنة
  وخمسين سنة. وحكى العباس ابن يزيد البحراني إجماع مشايخه على أنه عاش
  مائتين وخمسين سنة. واختلفوا فيما زاد إلى ثلاثمائة وخمسين سنة والله
  أعلم. والظاهر أنه قال لقد لقيت وصى عيسى بن مريم فهذا ممكن بالصواب.
وقال السهيلي: الرجل المبهم هو الحسن بن عمارة وهو ضعيف وإن صح لم يكن
  فيه نكارة. لأن ابن جرير ذكر أن المسيح نزل من السماء بعد ما رفع فوجد
  أمه وامرأة أخرى يبكيان عند جذع المصلوب فأخبرهما أنه لم يقتل وبعث
  الحواريين بعد ذلك. قال وإذا جاز نزوله مرة جاز نزوله مرارا ثم يكون
  نزوله الظاهر حين يكسر الصليب ويقتل الخنزير ويتزوج حينئذ امرأة من بني
  جذام وإذا مات دفن في حجرة روضة رسول الله صلى الله عليه وسلم.

English translation  by Trevor LeGassick

That, then, is how this anecdote is worded. There is (in its chain of
  authorities) one man of questionable reliability {unknown}, he being Sheikh { teacher of; from whom narrates}
  'Asim b. Umar b. Qatada. That link is also said to have been al-Hasan
  b. Umara. The tradition is also missing a link, indeed untraceable,
  between Umar b. 'Abd al-'Aziz and Salman, may God be pleased with him.
  As for his words, "If you have told me the truth, O Salman, you have
  met Jesus son of Mary," these are very strange, if not unacceptable.
  For the period involved must, by all accounts, be one of 400 years,
  perhaps even 600 years by the solar calendar. The longest anyone
  suggests that Salman lived is some 350 years. Al-Abbas b. Yazid
  al-Bahrani  related that the consensus of his elders was that he lived
  for 250 years;  they differed as to whether it could have been as much
  as 350 years.  But God knows best. And it seems that he was saying,
  "You met a (good) follower of Jesus, son of Mary." And that could well
  be true.
Al-Suhayli stated, "The man of questionable reliability (in the above
  chain of authorities) is al-Hasan b. Umara, a weak authority. But if
  he was correct, then there is nothing unacceptable about it. Because
  Ibn Jarir related that Jesus came down again to earth after he had
  been resurrected { raised up } and that he found his mother and another woman
  weeping at the cross of the crucified man. Jesus told them that he had
  not been killed, and after that he sent his disciples." He went on:
  "And if it is possible that he came down once, then it is possible he
  did so many times. Moreover there is his evident return when he broke {will break}
  the cross and killed {will kill} the pig and thereafter married {marry} a woman of Banu
  Jidham and finally was {be} buried in a chamber of the grave (usually
  referred to as the garden) of the Messenger of God (SAAS)."

Note that this translation contains several errors I've added some corrections in {}.

