3/m-Hydroxy benzaldehyde has been made by following methods:-

1. Reduction of m-hydroxybenzoic acid with sodium amalgam in weak acid solution; by oxidation of the arylsulfonic ester ArSO2OC6H4CH3 with manganese dioxide and sulfuric acid to the corresponding derivative of m-hydroxy benzaldehyde ArSO2OC6H4CHO and hydrolysis of the latter with concentrated sulfuric acid.

2. from m-dichloromethylphenyl benzoate by heating with water and calcium carbonate under a pressure of 4–5 atm. 

References:-

Org. Syn. Coll. Vol. 3, 564,

References and Notes

Sandmann, Ber., 14, 969 (1881).

Ger. pat. 162,322 (Chem. Zentr., 1905 II, 726).

Raschig, Ger. pat. 233,631 [Chem. Zentr., 1911 I, 1388; Frdl., 10, 163 (1910–1912)].

Tiemann and Ludwig, Ber., 15, 2045 (1882); Rieche, Ber., 22, 2348 (1889); Ger. pat. 18,016 [Frdl., 1, 586 (1888)]; Subak, Monatsh., 24, 167 (1903).

Org. Syntheses Coll. Vol. 2, 130 (1943).

General/Typical Procedure: Typical procedure: A mixture of 557 mg of benzyl alcohol, 0.15 mL of HBr (48%) and 5 mL of DMSO was stirred in an oil bath at 100 °C. TLC (petroleum ether/diethyl ether, 1:1) was used to indicate the completion of the reaction (3 h). To the reaction mixture were added 5 mL of brine followed by extraction with 30 mL of diethyl ether. The ether layer was washed with brine (5 mL X 4). Evaporation of ether and subsequent bulb to bulb distillation produced. 3-hydroxybenzaldehyde, yield 96%.

Looks interesting given the easy to get reagents and high yield.

Sudhir

Transformation of 3-hydroxybenzyl alcohol to 3-hydroxybenzaldehyde is reported >98%, see

--- Zamani, Farzad and Izadi, Elham, Journal of Inorganic and Organometallic Polymers and Materials, 23(6), 1501-1510; 2013

*General/Typical Procedure: Benzyl alcohol was selected as a model substrate for oxidation reaction and for the optimization of the process. A typical experimental procedure was as follows: to the mixture of catalyst [0.15 g, 17.5 % Cu(II)-cysteine/SiO2-Al2O3)] and benzyl alcohol (1 mmol), 4 mmol hydrogen peroxide (30 % solution) was added slowly and the reaction was shaken at room temperature in the absence of solvent. The progress of reaction was monitored by thin layer chromatography. After completion of the reaction, the catalyst was removed from the reaction mixture by centrifuge, the products and the unconverted reactants were analyzed by gas chromatography.  Solvent-free oxidation of various aromatic alcohols over Cu(II)-cysteine/SiO2-Al2O3. Reaction conditions: alcohol (1 mmol), H2O2 (4 mmol), catalyst (0.15 g, 17.5 % Cu(II)-cysteine/SiO2-Al2O3), solvent-free, room temperature. Time: 45 min, Yield: 98%.

You may also see

---  Massah, Ahmad Reza et al,  Comptes Rendus Chimie, 15(5), 428-436; 2012

--- Chandrappa, S. et al, Synthetic Communications, 38(15), 2638-2645; 200

Good luck

This will be reversed Cannizaro reaction.